How to Build a Garden Room Base – Step by Step Guide & Ideas

Top Mistakes to Avoid When Building a Base for Your Garden Room

Building a solid foundation for your garden room keeps it stable, level and damp-free. This comprehensive guide explains how to accomplish it in detail.

The Ultimate Guide To Building A Base For A garden room

Garden rooms are a must-have feature of any classic British garden. These sanctuaries allow you to appreciate the seasons’ grandeur while providing shelter from the sun, wind, and rain.

However, if you want your garden room to last, you must understand how to create its foundation. Otherwise, it may decay from the ground up, tip over, or become a victim of the wind.

Fortunately, you don’t have to figure out how to build a garden room foundation alone. This guide is here to help. It discusses the different types of bases for garden buildings, how to create your base, who to hire for base construction, and how to repair and maintain your installation. Everything you need is in one location.

Why You Need a Garden Room Base

When building a garden structure, bases are vital for stability and lifespan. Without a stable foundation, the structure is prone to shifting and settling, which can cause long-term harm.

Bases provide a flat platform for the building to sit on, distributing weight evenly and lowering the likelihood of structural concerns. They also help elevate the building, reducing contact with moisture and preventing rot and deterioration.

Investing in a solid foundation is critical to the building’s integrity and endurance. However, they still require a foundation – a robust framework that will allow them to function indefinitely. Without it, they will not last.

Longevity

The principal objective for building bases is to ensure structural longevity. Constructions provide moisture protection, preventing dampness from the ground from permeating the garden rooms’ hardwood floors and walls.

Keeping the structure dry decreases the risk of rot, mould, and structural distortion. It also makes the building more straightforward to maintain.

Level Ground

Bases also provide flat ground for these structures. Professionals construct these to form a flat expanse that allows the garden room to sit upright.

Without bases, garden rooms would be entirely dependent on the flatness of the earth underneath them. The earth must be precisely level throughout its duration to keep the construction straight and upright.

Bases prevent one side of it from sitting lower or at an angle from the others. This holds the structure upright, similar to foundations for traditional homes.

Stability.

Finally, these bases provide stability. Hard materials, such as concrete or pavement slabs, prevent the structure from shaking while people walk about inside.

Various Bases for Garden Buildings

Garden structures need a variety of bases to keep them level and stable. Your priorities, the climate, and other things will influence your choice.

The three basic base kinds accessible are as follows. We explore them and the benefits and drawbacks of each. By the end, you should have enough data to determine which choice is best for your project.

Concrete foundation

Concrete foundations are solid slabs put into the earth (often in an excavation). Installers utilise special tools to ensure the material sets smoothly, creating a solid foundation for the garden room.

Pros:

• Extremely stable and durable. Concrete is an extremely durable material ideal for outdoor use in exposed places. It is especially effective for heavier outbuildings, such as garden rooms.
• Long lifespan. Most concrete bases last for decades. (Some property owners still use concrete platforms constructed during WWII). Once installed, it frequently outlasts the structure it supports.
• Requires minimal upkeep. Concrete bases do not require treatment. Once in place, maintenance is beneficial but not required.

Cons:

• Drainage concerns. Concrete slabs can collect moisture beneath them, which can percolate into the material over time due to tiny porous holes.
• More difficult to install. Professionals do not recommend DIY concrete base installation. Excavating, soil preparation, curing, and levelling are only a few of the many intricate stages required in construction.
• Furthermore, correcting faults is difficult because it requires breaking up and reinstalling the concrete.
• Costly. Concrete bases are more expensive than other options (because of material and workmanship costs).
• The installation process is time-consuming. garden room owners must wait for the concrete to be completely set before erecting the building on top. This procedure can take days or weeks, depending on the product.

Paving Slab Base

Paving slab bases are simpler, consisting of slabs put over crushed materials such as gravel or with no sub-base (not advised). These provide many homes with a desirable look without the sturdiness of concrete.

Pros:

• Simple to alter. Installers do not have to lay paving slab bases properly the first time. DIYers and pros can experiment with each stone and the aggregate beneath it until everything comes together.
• Built-in adjustment. Owners can move pavement slabs over time in response to ground density and subsidence. Sub-bases can be easily releveled for paver relaying.
• Quicker installation. Aggregate foundations and paving slabs do not require any specific tools or equipment. Groundwork is still necessary, but it is less involved than concrete.

Cons:

• Less reliable. Paving slabs may slide and rock when the sub-base shifts, making any garden constructions less sturdy.
• Higher maintenance. Concrete bases remain consistent throughout their lifespan, whereas paving slabs might migrate or change height. Depending on the surrounding landscape, owners may need to relevel paving slab bases regularly, increasing maintenance requirements.
• Sub-base drainage problems. Paving slab aggregates may prevent water from draining adequately into the surrounding soil (particularly as they age). Sub-bases may require replacement (which entails raising the slabs, refilling the excavated area, and replacing them).

Timber sub-frame base

Timber sub-frame bases are constructed using treated wooden beams on concrete pads or foundations. The building sits on top of these, lowering the chance of moisture damage.

Timber sub-frame bases were more popular in the past because the material was widely available. However, it necessitates the construction of a concrete supporting structure.

Pros:

• Suitable for lighter soils. Wood bases weigh less, making them better suited to softer soils.
• It is cost-effective. garden room owners can add hardwood beams to existing concrete work, significantly reducing installation expenses.
• Easy to install. Timber subframes do not require curing or drying time.

Cons:

• Concrete must be pre-installed. Most timber subframes require pre-installed concrete pads or pillars to function properly. Others require bricks to form a barrier with the underlying soil.
• Poor durability. Timber is less durable than concrete because it is susceptible to moisture, decay, and burrowing insects.
• High maintenance needs. Timber sub-bases require continual preservative treatment. Accessing individual beams beneath a summer home to perform this maintenance can be difficult.
• Limited weight capacity. Wood beams are weaker than concrete and stone pavers, limiting their ability to support big garden structures above them.

1st Choice’s ‘No Concrete’ Answer with Timber Subframe Bases

Standard Timber Subframe Base
This is the ideal solution for garden sheds, workshops and garden rooms when the intended site is relatively level or when a base is needed to sit atop and level an existing concrete base; it is also very popular when access to the property is restricted or when people wish to avoid the disruption of concrete base construction.

A sturdy frame is constructed using 100mm x 47mm structurally graded C24 spruce, subjected to an enhanced pressure treatment process to improve its life.

To increase rigidity, cross members are placed at centres between 35cm and 42cm (14” and 16 1/2”) and noggins when the base’s width is greater than 1.5m (5’). The frame is levelled and supported on indestructible recycled plastic ground posts manually driven into the ground.

When the timber subframe is sat atop a concrete base, these plastic posts are not required, and chunky timber feet are used instead when levelling is required.

Heavy Duty Timber Subframe Base
Whilst our standard timber subframe bases are ideal for most situations, sometimes something more robust is called upon. This may be because the building is particularly large or heavy, the plan is to store a large amount of weight within the building, or simply because the ground on which the base is situated has more than a minor slope.

Whatever the reason, our installation team will upgrade the standard specification by upgrading the fixings to coach screws, digging out each post and concreting these into the ground and, where necessary, fitting diagonal braces to add rigidity to the joint between the ground post and the rame (when the base is elevated out of the ground). A wise upgrade when ordering a log cabin or other larger building; please ask our sales advisors for guidance if you need more clarification.

You can find more details here.

Consider these advantages and disadvantages When deciding on a base for your garden room. Manufacturers will usually advise you which base type works best with their items.

A Step-by-Step Guide to Creating a Garden Building Base

Some homeowners hire specialists to build garden bases. If you feel brave enough, you can do it yourself.

This method can be challenging to master, so strictly adhere to the directions provided. Deviating from them may endanger your garden room (or any other garden structure you place on top).

Site clearing and preparation

The first step is to clear and prepare the place for installation. Getting this right enhances the likelihood of constructing a long-lasting base.

Start by clearing the space. Remove anything that could come in the way of the building. For instance, make sure you eliminate:

• Grass
• Weeds.
• Shrubbery.
• Rocks
• Bricks.
• Garden waste.
• Compost.

The site should be devoid of anything other than earth. If you want your garden room to sit on your lawn, limit how much grass you remove. Taking away too much may endanger your appearance.

After you’ve cleared the area, measure the base’s outline. Marking where it will go reveals its footprint in your garden.

Most DIYers use a combination of string and stakes. You can also mark the area with paint, but let it dry first to avoid destroying the basic materials.

Always use a measuring tape to mark the contour of the base. When picking a footprint, remember to consider the shape of your garden room. Most units are square or rectangular, while some are hexagonal or octagonal, making base construction more challenging.

Ground Leveling

The next stage is to level the exposed ground. Making it flat makes it easier to construct the base.

Most terrain is not level, so you must consider the slope. Identifying minor peaks and dips allows you to assess whether you require complete levelling.

You may notice that the land is lumpy but generally level. Other patches have significant slopes and are more challenging to level.

If the site has a steep incline, consider building your building somewhere else. Slope removal necessitates extensive excavation, and new retaining walls may be required.

Earth must be added and removed to level slopes for garden buildings. Unless the slope is steep, ensure the levelled area is the same height as the surrounding region.

Use a shovel or rake to disperse soil across the land for smaller jobs uniformly. Removing soil from specific locations and depositing it in others can result in a more level surface.

Rent machines for more extensive operations. Diggers and tractors can level areas of land using various scoops and attachments.

Ground levelling is a complicated process that might take a long time. Be patient with it. If you aren’t satisfied with the levelling after one day, return to it the following and try again with fresh eyes.

During levelling, make sure the soil stays within your defined border. If possible, avoid removing soil from other locations.

Finally, ensure that the levelling does not harm drainage near the site. Don’t level land that slopes towards an existing building.

When preparing land, observe where the water flows. Check that it flows away from existing structures and into appropriate drainage channels.

Skilled garden-building base installers can level the land to slope slightly in the desired direction. However, you should only do this if you have the ability and motivation.

Weed Membrane Installation

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In rare cases, it may be required to lay a weed membrane. Putting it down keeps persistent weeds from penetrating the soil and destroying the subbase.

Do not use ordinary weed membranes. These are more robust and durable to protect your garden building. Use items designed exclusively for garden rooms, then put them over the base area’s edges using the supplied fittings.

Allow the soil to compact.

After you’ve finished levelling, give the dirt time to consolidate. Allowing it to squash removes air pockets and increases stability.

Unfortunately, passive soil compaction may take weeks or months. To work faster, professionals employ a variety of compaction instruments. These continually press into the dirt, pounding it in place.

Compaction equipment can rapidly identify differential densities in your soil foundation. If you observe any development, add more soil, rake it over, and continue compacting.

When compacting, be methodical. Begin at one corner and move in lines until you have covered the marked space. Continue continuing until the soil stops moving.

If you don’t have any compaction tools, you can rent them from a nearby builder’s yard or equipment store. Compacting land to an adequate density should take at most a day.

Add the base material.

Once you’ve prepared your garden base, the next step is to add the base materials. Here are the three base materials and how to install them.

The Concrete Base

Concrete preparation is the first step in installing a concrete basis. You can use ready-mix concrete (made in a mixer) or bagged concrete for a modest garden construction.

You’ll also need:

• A spirit level.
• Edging boards
• Crushed rock sub-base
• Mixing tools
• Wheelbarrow.
• Shovel
• Goggles and gloves

Excavating for concrete bases is only sometimes necessary. As a result, you may need to dig into the dirt.

Most experts recommend digging down 100mm (about 5 inches) if you have moist soil or wish to construct a large building on the base. Once the excavation is finished, you can add the aggregate. It will function as a base drainage system, preventing rising water from causing flooding or other harm.

Formwork may be required in big concrete base projects. Edging boards border the base’s boundaries and keep the concrete in place while it hardens.

After these preparations, it’s time for the concrete. Mix according to the manufacturer’s directions (concrete mixing varies greatly between brands).

Once mixed, pour the concrete fast. Leaving it too long may lead it to set before entering the base.

Pour the concrete into the indicated base area. You will observe it spreading to occupy the available space. (If it is too thick, it will not spread, and you should make a fresh batch).

For big bases, utilise a concrete pump. These move large amounts of material from a truck to the nozzle, avoiding the need for wheelbarrows and other temporary solutions.

After pouring the concrete, level it to make a smooth surface. Most do-it-yourselfers utilise a screed, which is a simple portable equipment. Rake it over to ensure the concrete is level with your edging boards (if using them).

The concrete should slope slightly away from nearby buildings to ensure efficient drainage. A perfectly flat surface may cause water pooling or surface run-off in the wrong direction.

The final step is to finish and cure. Concrete needs time to set correctly.

Most products dry in 24 to 48 hours. However, some concretes may take up to 28 days to attain full strength.

While the concrete is curing, some specialists erect buildings on top of it. This strategy is dangerous since the weight of the building may leave impressions on the concrete. Always follow the manufacturer’s directions. Please only use a concrete base once it’s ready.

Paving Slab Base

Installing a paving slab base necessitates a different strategy. The first stage, like with concrete, is to gather your ingredients. You’ll need:

• Paving slabs
• Crushed rock.
• Sharp sand
• Spirit level.
• Rubber mallet
• A mortar-like compound.

Once you have the materials, the first step is to lay the sub-base. This phase is almost identical to concrete. You begin by excavating the ground to a depth of 100mm and filling it with hardcore appropriate for the weight and dimensions of the garden room.

Next, add the sharp sand. It provides a soft and even bedding material for the pavers. (Concrete does not need this step because it can fill gaps surrounding the aggregate).

After that, lay the slabs. Professionals usually start at one corner and work their way around.

When putting every slab:

• Make sure it is even with the spirit level.
• Make sure it doesn’t wobble from side to side.
• Make sure it matches the general pattern or impact you want to create.

If a slab isn’t level, push it into the correct position with a rubber mallet. If required, sprinkle more sharp sand underneath or around the slab to provide additional support.

The final stage is to “join the slabs,” which involves filling the gaps between them using a mixture similar to mortar. Do not create the compound yourself. Instead, utilise the one provided by the vendor.

Sometimes, a slab breaker will be needed to cut slabs into the right shape. These machines use diamond-edged cutters to hew through the rock and break it into smaller fragments.

If you are hesitant about this phase, hire a professional to pre-cut slabs based on your foundation plan. This technique decreases risks while increasing the likelihood of positive outcomes.

Timber Sub-Frame Bases

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Timber sub-frame bases are the easiest to build and require the least specialised equipment. To build a timber sub-frame foundation, you will need:

• Pressure-treated timber beams that are appropriate for the weight of your construction.
• Concrete foundation blocks
• Screws are included.
• Drill
• Spirit level.
• Saw
• Sharp sand

If you are still determining whether the timber is suitable for your garden room, consult a timber trader. Experts can recommend the best outdoor wooden beams to utilise.

The first stage in installing the timber sub-frame basis is to place the concrete blocks or pads. If you don’t already have any, you’ll need to drop them into the ground and space them properly for the weight of the building. Check that they align with your spirit level; if not, add sharp sand.

Next, cut and install the timber beams (unless you purchased pre-cut timber). Cut pieces of wood to the desired lengths using a saw (or another wood-cutting equipment). Using the drill and screws, assemble the pieces of wood according to your idea.

Finally, the completed foundation will be installed on the concrete pads. Use L-shaped metal brackets and secure them using concrete-specific screws.

Who should build the base?

There are two alternatives for building a base for your garden room:

• Do-it-yourself with aid from pals.
• Professional “no-nonsense” experts provide peace of mind.

Building the basis yourself is less expensive initially, but the hazards are more significant. While your buddies may appear capable, the mistakes they make now could cost you later.

People with extensive building or construction experience should build bases for their holiday homes. If you’ve done work like this before, there’s no reason you can’t apply the same concepts to your property.

All three bases mentioned above demand specialist construction knowledge. Conversely, concrete variants are undoubtedly the most complex because they require specialised equipment and expertise in levelling and curing.

Adding a timber sub-base may be a do-it-yourself project if you already have concrete pillars or pads (or supporting masonry). However, you must strictly adhere to layout plans and use the appropriate beams (heat and pressure-treated).

You may benefit from a professional “no-nonsense” approach if you have never built a garden room base. This strategy is more expensive initially, but it may save you money in the long run if you make mistakes.

Professionals, for example, provide their skills to construction projects. Unlike do-it-yourselfers, they have years of expertise completing similar jobs and understand all aspects of site preparation.

Better still, they can complete the work faster. Professionals spend less time on easy tasks and move quickly to complete projects.

Furthermore, hiring specialists rather than friends will produce higher-quality results. Professionals must stand behind their jobs and deliver high-quality results to get rewarded. Someone you know in the community does not have to adhere to the same norms.

Finally, employing professionals is safer. Experts remove paving slabs and pour concrete daily, so they know the risks. Amateurs may not. Splinters, stumbles and falls, and back, neck, hand, and toe injuries are all possible side effects of DIY work.

How Can First Choice Help You?

We at 1st Choice specialise in offering an extensive collection of quality timber, concrete and metal buildings, so you can be assured that you will find your ideal building with minimal fuss. There are occasions, however, when other specialists are required to complete your project, and our years of experience in this field mean that we have built up several valuable connections with reliable tradespeople whom we have put forward here for your consideration.

Whilst the individual tradespeople are independent of us (thus keeping the pricing as low as possible), we are happy to liaise with them to make arrangements on your behalf. We, therefore, take a deposit, which is passed along to them with your order. Upon completing the work, they will collect the outstanding balance and leave you an invoice for your records.

Prices quoted presume a suitable, accessible work site within 50 miles of our display area near Woking. If your site is further afield or access is poor, the standard quoted prices may be subject to an additional charge. You can find more details here.

Tips for Maintaining and Repairing Garden Building Bases

Garden-building bases are typically reasonably sturdy. However, they still require routine maintenance.

But what should you do? Let us find out.

Inspections are conducted regularly.

Regular inspections are essential for proper maintenance. Checking your base for damage prevents minor issues from escalating.

During an inspection, you should search for the following symptoms of damage or disrepair:

• Damp spots persist even in warm weather or after storm waters recede. (Damp spots will be darker on concrete and wood).
• Concrete pads or beams that wobble or move when touched.
• There are cracks at the base.
• Rot in wood-based materials
• Place bases at a different angle than when installed. (Bases can occasionally shift owing to ground movement or subsidence).
• Soil pushing on the base or bottom of the garden room.
• Cracks or cracks in the jointing material of paver slab bases.
• Uneven paving slabs.
• Evidence of excessive aggregate or sand washing out from under the foundation (typically in the direction of draining water).

Most examinations will discover no concerns with your base, provided it is correctly designed. However, keeping an eye on it is essential because problems can be expensive to address if left untreated.

Repairing cracks or damage.
Cracks in garden room foundations can be a reason for concern. However, your actions should be proportionate to the gravity of the situation.

Concrete

Minor hairline fractures in concrete are probably not worth worrying about. However, note them and take action if they become worse.

However, fissures in concrete less than 6mm (approximately a quarter of an inch) must be filled. Leaving them can cause freeze-thaw weathering, in which ice freezes within and expands, pushing them apart. Over time, this process might cause structural damage.

To fix a concrete fracture, remove any debris around it, such as leaves, soil, or twigs. Next, apply a concrete filler. Ensure that the filler is fully inserted into the crack. Filling it eliminates dangerous water intrusion (which leads to the freeze-thaw deterioration described earlier).

Most professionals advocate applying flexible sealants to the repaired area once it has dried. These can expand and contract with the underlying crack and filler, effectively waterproofing the patch.

Paving Slab

Paving slab bases may also crack. The fix you implement, like with concrete bases, is determined by the severity of the damage.

You can repair uneven slabs by adding or removing sand beneath individual pavers. However, accessing them may necessitate moving your garden room from its pedestal.

Replace and rejoin any significantly damaged pavers. A single fractured paver can also be turned into two slabs with suitable jointing. Just make sure it’s not load-bearing.

If you detect several cracks in your paving slab base, this could indicate earth movement or subsidence. Unfortunately, this circumstance may necessitate a complete reinstall on more stable terrain.

Timber Sub-Frame Bases

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Finally, timber sub-frame bases may crack in certain instances. You will need to fix any non-superficial damage.

If you find a slight crack in a beam, sand it to see how deep it goes. Superficial cracks sometimes appear to be more severe than they are.

If the crack deepens, replace the beam. Unscrew it from the rest of the structure and replace it with a fresh piece of wood that meets your standards.

Cracks might emerge due to decay or insect damage. If this happens, look for signs of humidity and insect damage. Also, make sure you treat the beams correctly before installing them. Most insects will overlook preservative-coated timber beams.

Water damage prevention

Preventing water damage requires preventing it from reaching your base in the first place. Therefore, consider the beginning of the construction procedure.

The most straightforward approach to prevent water damage is to design the base to slope in one direction away from your buildings. A slight slope helps water to drain while providing a solid foundation. As previously stated, establishing a shallow angle while providing a solid foundation for your garden room is difficult, so many homeowners use professionals.

You can also avoid water damage by installing sufficient drainage around your building. Using an adequate subbase, drain lines, and gullies will allow your garden room to drain extra water during downpours. During your checks, look for drainage that drains into the surrounding land and rivers. Slowing the run-off can help prevent flooding and keep water from entering the excavated area.

Finally, consider the materials you use. Most professionals use waterproof concrete for their foundations. These include chemicals that keep porosity holes from forming during the curing process. Waterproofing prevents moisture from permeating the substance, even in standing water.

Treating wood also helps to avoid water damage. Do this every few years or so.

Conclusion

After reading this tutorial, you should better understand the importance of a solid foundation for your garden room. Keeping the structure above it stable, level, and damp-free is critical.

However, achieving it right necessitates understanding what you’re doing. If you need more clarification, consult a specialist.

Consider the best base if you’re considering creating a garden room. In some cases, concrete may be preferable over paving slabs. Also, consider the weight of your garden construction and the soil type.

What are you waiting for if you still need to start your garden room base project? Start your project today and create your own beautiful hideaway.

Frequently Asked Questions (FAQ) Garden Rooms