The Top 10 Most Common Mistakes When Building a Summerhouse

There are many reasons to build or erect a summerhouse. Summerhouses have become more and more popular in the UK for a variety of reasons.

However, the road to such a wonderful garden building can be rough and full of snares. So we have collected the 10 most common mistakes when building a garden building, like a summerhouse. We try to cover self construction as well as erection of a pre-engineered summerhouse. While many snares are within the construction process when going fully DIY, some mistakes are common for both kinds of buildings.

Mistake No.1 when building a summerhouse: planning poorly for the future

Right in the very beginning stages, the planning starts with you taking an in-depth look at the use you wish to dedicate to your new summerhouse. Life changes permanently and so do the ways that a summerhouse can make sense in your and your family’s life. So the idea should be to plan the summerhouse in a way that enables an evolution in the way it is used following the family’s ever changing needs.

So as to size, wall thickness and glazing, it might be important to provide for evolutions of use in the future and plan a multifunctional building from the start. If you think, it should be possible for the summerhouse to be permanently inhabited at any time in the future, then the wall thickness should be at least 28mm. A better choice would be 40-50mm because these wall logs have double tongue & groove and allow for larger buildings with greater stability and they also provide a solid basic insulation that can easily be improved.

Of course we would also like to mention that our new line of large garden log cabins called „Holiday Line“ come with 92mm log thickness and double glazed Roto windows and doors made in Germany, which would be a perfect choice for a summerhouse of great durability and the option to insulate and use during the winter as well.

Mistake: No.2: disregarding building regulations and planning permission

Even if your summerhouse is below the threshold of 15m² and the overall height is less than 2,50m, our advise would be to contact your local planning office with the details of your planned garden building, just to be on the safe side. If you take our advice to plan for a bigger summerhouse to be well prepared for future developments, then it also should be no big deal to get the proper permissions for a large garden building with multi-functionality options, but you will have to take the time to get all the paperwork done correctly. Usually that should be possible in 4 to 6 weeks.

To finish this stage properly you should also already have planned the exact position in the garden, where your new summerhouse will be both: fully functional and good looking.

Mistake No.3: going for the cheapest price and choosing the cheapest timber

Building a summerhouse with inadequate, low-quality lumber is a recipe for certain failure. Your summerhouse will not only be subjected to rain, wind, fog and sun but also be a target for insects, moulds and rotting so the right timber is essential for durability and low costs of maintenance.

Even though local Pine, Ash or Fir might be cheapest, the more durable species are unfortunately more expensive. Oak or larch would be perfect of course, but these are unaffordable for most. Redwood, Cyprus or Cedar are also among the more expensive ones but are generally the better choices. Also try to get heartwood instead of sapwood and be aware that wood should be well seasoned.

If you order a prefabricated summerhouse from one of the manufacturers in Northern Europe, then please note that neither local Pine nor local Spruce compare to the Nordic species, which are much slower growing and have much higher density and durability.

If you buy your own building material, aim at straight, tight-grain material.

A good idea would also be to use pressure treated beams for the lowest parts touching the base and also treat them with wood oil or stain.

Mistake No.4 : building the wrong base for your summerhouse

Whether you plan a wooden floor for your summerhouse or you plan to use a foundation, as for example a bedplate or a foundation slab as the floor of your new garden building, you should keep one thing in mind: There are really strong storms which even might get stronger due to climate change and a wooden building like a summerhouse doesn’t have enough weight on its own to stay on the ground by itself. So the clever thing to do would be anchoring the building to deep foundations at 4 to 6 points according to the size of the building.

Additionally you might plan vertical wooden anchors up the walls, so that the tongues and grooves which usually stay together due to the weight of the upper parts of the summerhouse are not torn apart during a strong storm. These vertical anchors cannot be fixed to the walls because they have to allow for the settling of the building when the wood gets older and dryer.

A higher foundation might be good, because foundations made of concrete can’t rot away like the lower planks of your summerhouse could, when they get drenched by rain, wind or covered by plants decorating the summerhouse. So if the lower 20 – 50 cm of the height of your garden building consist of a concrete foundation, this will be a very good protection for the lower wooden parts as the spray-water from rains and storms will land there instead on the wood.

Mistake No.5: planning a summerhouse with a concrete floor

Why is this a mistake, you might ask. A proper foundation has to be made anyway so why not spare the costs for the wooden floor and use it as a cheaper alternative?

The answer is: Comfort and moisture. A wooden floor is much warmer and cosier than a concrete one. If there is any possibility that you might ever want to use your new summerhouse as an extension of living space, then a wooden floor is just much better for comfort and insulation against the cold ground. It also looks much better and spares heating costs, if you ever want to heat inside.

Good drainage is a must for any foundation, but still a concrete floor will hardly ever provide the same protection against moisture creeping up from below as a wooden floor above a well drained and protected foundation can. Remember: you want to erect a wooden garden building and so moisture should be one of your main concerns. Also for anything that can rot or rust inside the summerhouse, the dryness provided by a wooden floor will be most beneficial.

Mistake No.6: missing know-how building the roof of the summerhouse

Keeping the wood dry is the number one protection for any wooden summerhouse, so without going into the details here, because there are so many ways of roofing: be sure, to use a proven method. It might not be as easy as it seems to keep the rainwater out.

Another thing to consider is to plan for large roof overhangs in order to keep the rain away from the walls. Finally it is vital to anchor the roof firmly to the rest of the wooden garden building to make it stormproof. A few nails or screws won´t be enough. You should work with angle steel or metal plates with drill holes.

Mistake No.7: neglecting the wood proper care

This begins in the early stages of the construction of the summerhouse. The floor boards should consist of pressure treated timber and you should treat them with a wood impregnation beforehand, because this will be all they get during their lifetime, because these parts might not be accessible after the construction.

All parts subjected to the weather should be treated with wood preservation agents every few years. If you want to keep the light brown colour, you might also consider an agent with UV-protection to prevent your wood from becoming grey.

Mistake No.8: not taking into account the settling of the summerhouse

Wood shrinks when it gets older and dryer and this means, that you have to construct the whole summerhouse with this knowledge in mind. For example you cannot use expanding foam to fix the window frames. Instead they have to run through a groove at the end of the logs or planks of the walls. You need to install a “T” section as part of the frame to be able to slide through the groove when the settling takes place. Also leave a 2 inch gap at the top of the frame and fill it with a flexible material as fibreglass or wool. The same of course applies for door frames.

Mistake No.9: disregarding proper structural analysis: statics of the summerhouse

According to the roof pitch of your summerhouse, specialists can figure out the correct measurements of the timber you construct your garden building with, so your summerhouse will be able to bear not only the weight of the roof but also additional snow on its top. For example the strength of the rafters will be figured from the kind of timber (wood species), length of the rafter and expected weight load.

If you want to keep the option open to maybe one day install solar panels on the roof to enable off-grid electricity in your summerhouse, you should figure the weight in from the start. The same is true, if you want to make a flat roof into a green one, to provide some food to bees and birds with plants on the roof.

Mistake No.10: negligence to the fact, that bad guys might want to break into your summerhouse

As a matter of fact, it is enough to make the break-in look too tedious or loud. There is no one hundred percent security against burglaries and most burglars are just looking for easy opportunities. Some easy measures are: cylinder locks for doors and windows, one or two motion detectors could switch on the exterior lighting or even sound an alarm, or adhesive foils to glue on your windows to make them unbreakable.

Other pieces of advice are: Don´t let gardening or DIY tools lay around in the open for the intruder to use and keep a good relationship to your neighbours. Exchange telephone numbers, so that in case of any event you would alarm each other.

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