In my previous post, I described in detail how to build a BillyOh Kent garden office log cabin. Now I’ve made progress on the building and it’s ready to use as a fully insulated garden room, complete with electrical sockets, lighting and heating so that it can be used all year round in comfort. Read on to see how to insulate your BillyOh garden building.

This specific building is the BillyOh Kent Garden Office.

The BillyOh Kent garden office is a great building designed and produced by Kybotech Ltd. based in the UK. It is a customisable garden building available in a number of different sizes at a very reasonable price. That’s what makes it so appealing. We wanted a workspace in the garden but the costs of a professionally built garden room was a bit too scary. So I challenged myself to build my own for a fraction of the cost. In total this build has cost us about £5800 whereas a similar size build from a garden building company would cost in the region of £20,000.

Visit my BillyOh Kent building post to see this build from start to finish. I have included links to all the materials used within this project. (links will open in a new tab)

How to insulate your BillyOh log cabin

For my building I decide to use a 25mm Celotex insulation board. These boards provide a good level of insulation, are easy to work with and are cost effective. You can get thicker boards but I wanted to retain as much of the interior as possible. Another good alternative is this Recticel Instafit Polyurethane Insulation board.

Firstly I fixed some 25x50mm battens around all the corners of the building. This is where the plasterboards would be fixed to. Make sure you run these around the whole interior edge. See below image. (50mm side flat on the surface) This timber from B&Q is also suitable.

For the wall corners you will need to put two lengths next to each other so that there is a fixing point on both walls. Here is a cross section view for the corners timber frame.

This will create a 25mm deep recess in which the insulation boards can be fitted. The insulation boards can then be cut to size using a sharp knife. I used a utility knife for this. I measured up the height of the recess, marked it out on the board with a pen and cut with the knife.

Save any off-cuts at this point as they will be required later on.

I continued around the room with the same process. Measuring and cutting to fit in the recess.

The boards are not fixed to the wall at this point. The plasterboard will hold them in place later.

I worked around the main incoming electrical cable. This was a thick cable. I cut out some pieces of Celotex to fit around the cable making it as neat as possible.

I continued fitting insulation boards all the way around the room. Cutting sections to go around the windows and door frames.

You will notice that the window and door frames are about 20mm thick which isn’t going to work when fitting the plasterboard. Therefore I cut some 5mm strips of wood to go around the frames to bring them up to 25mm. (The same as the rest of the recess framework.)

I also cut another piece of wood (25x30mm) to fit around the frame which would create a barrier for the plaster to sit up against. These pieces were nailed into place with some thin lost head nails.

Fitting the electrical cabling

I decided to fit the electrical cabling for the sockets after the insulation boards were fitted. This would be easier, rather than trying to measure and cut the insulation boards around the cables.

A channel was cut into the insulation board using a sharp utility knife. The socket back boxes were then measured up and cut out using the same knife.

All cables ran back to the main fuse box. (Consumer unit)

I have a lot of off-cuts left over from the insulation boards so I decided to fill the ceiling with these. There was almost enough to cover it all.

Fitting the plasterboard

Before you go any further it’s a good idea to fit a vapour barrier to all the walls. This will prevent moisture building up behind the walls which can cause issues with the plasterboard.

With all the insulation fitted, cables run and frames modified it was time to move onto the plasterboard. Measuring and cutting the plasterboard is similar to cutting the insulation boards. However, you won’t need to cut all the way through a plasterboard sheet. Simply cut one side and then snap the board along the cut line.

The plasterboard is fixed into place using drywall screws. I used 35mm screws around the edges, were the boards sat up against the wooden frame. I then used 50mm drywall screws to fix the centres of the boards. It’s important to make sure all the boards are fix securely. Any movement can crack and crumble the plaster once skimmed.

Cutting plasterboard around window frames was a little more difficult. As in above image I had to cut all the way through the board. i couldn’t use the cut and snap technique as before.

Light switch and socket back boxes can then be measured and cut into the plasterboard.

Plastering the interior

With all the plasterboard now fitted it’s time for skimming the walls. I hired a professional for this as they can do it to a high standard much quicker than I can. The cost for this was £250 for all the walls. It took him about 6 hours to complete the whole lot.

It’s important to let the plaster fully dry before painting. This can take about 5-7 days depending on the weather. Don’t get impatient and paint it before this or it will likely crack. The first two layers of paint should be done with a watered down emulsion (50% water /50% paint)

Here it is after one day. Drying slowly.

With the plaster fully dry it’s time to get on with the painting.

Painting the walls

Following on from the plastering I applied two very wet coats of paint and two normal coats. The first two coats of paint were 50/50 water and white emulsion paint. This prevented the paint from drying too quickly and cracking.

Fitting the laminate flooring and thermal underlay

The underlay I am using for this garden building is a special thermal underlay to add some further insulation to the room. I already had a layer of insulation under the floorboards so this is an extra layer for further thermal protection.

After sweeping and vacuuming the floor it was time to roll out the thermal underlay. To help out I used a staple gun to hold the pieces in place.

This roll includes a 100mm overlap so you can create a good vapour barrier. No need to add any extra barrier.

With the underlay in place it was time for the laminate flooring. We opted for a thicker laminate board for that bit of extra insulation.

The final stage was to add skirting to seal the gaps around the lanimate flooring.

Insulating and finishing the ceiling

As mention before the ceiling is mostly insulated with the same boards as the walls. I did however run out. Rather than buying another board I decided to fill the other areas with recycled insulation materials. This is a great money saving and environmentally friendly approach. I used polystyrene sheets and other packaging materials for this purpose.

The whole ceiling was then cladded with a spruce tongue and groove timber. Each piece was cut to length and nailed to a retaining timber runner that ran down the walls and rafters.

It took a while to cut all the pieces but here is the finished ceiling. I’ve also added some more insulation to fill as many gaps as possible.

I’ve now had a good chance to see how this building performs in some real hot weather. I’m happy to say that the insulation is doing it’s job. The garden room stays pretty cool for most of the day. I noticed the temperature creeping up later in the afternoon when the sun was at its hottest. Outside temperature was about 33 degrees whilst inside it reached about 27 degrees. This level of heat was manageable with a 12” desk fan.

Wrap up

So there we have it. How to insulate your BillyOh garden office, shed or log cabin. It goes to show how easy you can transform a garden building into a functional room that can be used all year round. With a little investment, you can achieve this with most of the BillyOh garden building range.

Tool shed side extension

I’ve recently added a small side extension storage tool shed. This provides space for my tools and a few other bits. It’s a great addition and was easy to construct with some 50x25mm timber and some cladding. For the roof, I used some leftover polycarbonate sheets from my veranda build.

My next project will be to install a log burning stove in our BillyOh garden office. Stay tuned for the latest updates.

Here’s a little video tour of the finished building.

Thanks for reading. Please feel free to ask me any questions about this build using the comments section below.

Why not try one of these related posts:

• How to build a veranda: Step by step with pictures
• How to build your own veranda for under £500 – DIY veranda
• Looking for a cheap desk? 15 Cost effective alternatives to Ikea desks
• How to build a raised planter with seating
• How to build a shed from scratch on a budget