Battening and insulating the walls

I spent yesterday and today battening the internal walls. The first step was to effectively wrap the walls in a breathable membrane. This would help to prevent condensation forming, however it shouldn't be an issue as I'm using the same 'warm' method used for the ceiling. This will mean there is no air around the wall, thus condensation can not form. To be on the safe side though, the insulation will be sealed in with silver foil tape, preventing any form of air movement.

Once the membrane was up, I started on the stud work.

To get the correct widths, I cut a sheet of Celotex in two lengthways, creating a 600mm width (or near enough to 600mm as the sheets are ever so slightly smaller than that), and basically used it as a guide as to the distance between battens.

Once the vertical battens were in place, I placed a single noggin across the middle of each. 

The same was done for the back wall, the only difference being that smaller gaps were used between the vertical supports. 

For the left hand wall, I opted to use two sets of noggins as this wall will likely have a cupboard on the wall, in addition to monitors mounted on it. Because of this, I've basically strengthened a few parts of it to allow for heavy loads to be supported. 

I've opted not to add the insulation to this wall just yet as the electrics need to be added. I've also not yet sealed the insulation in place yet as I'm waiting for some more silver foil tape to be delivered (damn you eBay!).

Once the walls are sealed up, I'll get the right and back wall covered in plasterboard.

At this point you may notice I'v not talked about the 'front' wall (I.E the wall with the door and window). I had a bit of a problem with this one. The door and window that came with the shed have a 1.5cm frame built into them. The floor bearer does not. Meaning that the roof bearer is 1.5cm out. So I basically need to add a 1.5cm piece of wood across the top, to support the plasterboard. I've actually got a ton of spares from the shed build so hopefully I can find something half decent to use for this. Once that's done I can get that wall insulated and boarded up. Thankfully there will be no major weight load on this wall, just plasterboard, otherwise it could have cause a potentially annoying problem resulting in an odd shaped wall.

Finally, taking the idea from someone else who is currently converting a shed (whom I met via the DiyNot.com forums), I've decided to add a 'lessons learnt' section to each post, basically saying what I screwed up or would do differently next time, so here it is:

Lessons Learnt

1. Never underestimate the amount of wood and screws you'll need. I did three separate trips back to Wickes to get more supplies!
2. A staple gun is very helpful when putting up a breathable membrane. You still need to seal it to the wall with a waterproof tape (I opted for duct tape) but it helps hold it in place while you get it all lined up.
3. Cutting Celotex is a pain. If using a saw, get one with extremely fine teeth. I found a kitchen knife (The kind they use in Subway to cut sandwiches - very sharp!) to generate zero dust, compared to a saw, which got it everywhere!

Photos

The full set of photos so far can be found on the Flickr Page.

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The end does seem to be in sight. The main big jobs remaining as of this post are:

• Seal the insulation on the right and rear wall
• Sort out the 1.5cm gap on the front wall, and add insulation
• Plasterboard over the front, right and back wall
• Get the electrics fitted on the left wall
• Insulate (and seal) the left wall
• Plasterboard the right wall
• Skim over the plasterboard gaps
• Paint the room
• Add the flooring
• Add a skirting board
• Move in!

Actually, when you put it into a list, there is still a hell of a lot to get done. My feeling is that once the electrics are in place I'll be finished in no time. However while I'm waiting for the electrics to be done, I can still get the three other walls finished.

One thing I also want to do at a later stage is add a seal around the roof. I noticed that the roof edging boards do have a very tiny gap, meaning water can trickle under them. It would never get into the shed as its on the overlap, however I've bought a bitumen sealant that is designed to fill gaps around fascias. I'll likely also add some extra sealant on the joins of the roof felt just to make me feel that bit happier about it being water tight.

Ceiling Done!

I (well...we) got the plasterboard up on the ceiling today...what a hellish task that was! Couldn't believe how hard it was to get it to go up, but got there in the end. The shear weight of the boards combined with the fact that we had to get them to fit perfectly made it a tiring task.

I've also modified my plans slightly. To speed up the process, I've opted to just go for 3 double sockets on one wall, and nothing on the other 3 walls. This means I can get three walls completely insulated and plasterboarded and then get the electrician to work his magic on the final wall. I was originally planning on four double sockets (2 on each of the 12ft walls) however I really don't think I'll need it, and can always use an extension lead if I need more.

I also opted not to have a ceiling light as I've previously found that you can get away with a cheap-ish Ikea up-light in the corner. I'll then top it off with a couple of desk lamps, these will all use a strong white light bulb instead of a standard yellow-ish bulb. This should help a lot as I'll obviously be using the room as an office, so want a very crisp, clear light in there.

I've not got photos of the plasterboard up yet as it started pissing it down with rain just as I finished.

One really annoying thing I found was that because of the odd spacing on the roof batters, we had to cut the plasterboard in odd places to get it properly supported. We then had to add the top of the wall supports just under the plasterboard to give it extra support around the edges. In all it took about 2 and a half hours. Once the room is pretty much finished, I'll add joining tape and then skim over the gaps. I'll then probably line both the walls and ceiling in a thick lining paper before painting.

Next on the list is getting the wall studs in place, weather permitting, I should be doing it tomorrow.

Insulating the roof

When it came to the roof insulation, my original plan was to use 100mm Celotex, and have a 50mm air gap above, creating whats known as a 'Cold Roof'. Soffit vents would then be placed at each side of the shed, to allow airflow on the upper side of the celotex, preventing condensation.

BUT. I messed up. I went to fit the 100mm celotex, to find my rafters were only giving me 120mm gap, meaning my air gap could only be 20mm, which would not be enough.

Because of this I opted for a kind of 'hybrid warm roof'. A breathable membrane is attached to the roof from the inside, coating it completely. The 100mm celotex is then placed between the rafters. At this point there will be little to no gap between the Celotex and the plasterboard that'll be added later.

I sealed up any gaps with expanding foam, and used Celotex Foil Tape to completely seal the gaps around the celotex. This means no air can get above the celotex, thus there should be no condensation.


The only downside to this method is that an air vent has to be placed somewhere inside the shed to avoid condensation building up on the ceiling. I'll likely place a small vent above the window or door, assuming I can find one that is small enough.

If this was a house build, this method would probably not work, however since its a one room shed conversion, it shouldn't cause any problems with thermal bridging so long as sufficient ventilation exists inside the room.

So far I've got the celotex up and secured, I've now just got to place the plasterboard on the ceiling and can then make a start on the stud work walls.

I had to wait until now to start the stud work as the building has a sloped roof, and it would have been near impossible to work out how high each wall joist needed to be without having the roof completely finished.

Once I have the studs in place, I'll be calling an electrician in to get the power fitted, as I assume this will need to be done before I add wall insulation.

The end is in sight...weather permitting I should be able to get the stud work done over the next week. That being said, given the weather over the previous few days I'm pretty doubtful. I came very close to going out and buying one of those white plastic gazebos so I could continue working!

Insulating the floor

For the floor I opted to use 50mm Celotex PIR board. This should provide a decent level of insulation underfoot.

I started by lining the floor (Which was basically the HawkLok shed base, and the floor rafters) in a damp-proof sheet. Basically this is just a very thick black plastic sheet. It covered the floor completely, and will stop any water from under the shed damaging the insulation.

The Celotex was laid between the rafters. To cut the Celotex up I used a standard saw, however a kitchen knife or knife with a vert fine set of teeth will be better, and leave much less dust - never, ever cut Celotex up without an asbestos-grade face mask. It's not in any way cancerous, but it will cause breathing problems for a couple of days, and from my research it turns out that the cheap paper masks dont actually do bugger all, so make sure its asbestos grade (they are around £5 each).

Once the insulation was fitted, any gaps were filled with expanding foam. I didn't need to worry about using foil tape around the edges as the celotex was on the sealed plastic sheet, so no air or liquid restriction was needed.


The floorboards were then laid from front to back, they interlock a bit like laminate flooring but are made of solid wood. They are then nailed down to the rafters.

I was actually pleasantly surprised at how stable the floor was. I expected a bit of 'bounce' to it, but it was pretty rock solid.

Once the floor was done, it was time to work on the ceiling, which I'll cover in the next post!

Building The Shed

Well the shed arrived last Thursday, direct from Shire.

I have to say that I wasn't impressed by the delivery service. The driver pulled up and had the shed wrapped up on the back of a truck, with a crane. It took him around 45 minutes to unload the shed. Towards the end I had to go and help him as he very nearly dropped it on my Dad's car, despite me asking the driver if the car needed to be moved, which he said it did not. He used two large bands around the palet containing the shed, and as he lifted it, the shed nearly slid off the end. A very poor start, but we got there in the end.

After he left and I started unwrapping I noticed a lot of broken pieces. Thankfully as it turned out it wasn't as bad as it looked, and there were ample spare parts.

One thing I will say: Shire sheds have the WORST instructions ever, they really may as well not bother sending them out. The entire instructions seem to be the same for their entire product lineup as many of the points were totally irrelevant. The wording was pretty poor (e.g 'Drill hole aprx 50 centers from the side' and 'Place WT next to WA and line up WC at the end', without any instructions saying what 'WT' 'WA' or 'WC' was).

Had the instructions been written by someone a little more competent, the shed would have been up within 2 days. As it stood, it took three.

The actual building went together fairly easily. The logs locked together well, and I was very glad that I had opted for the thicker wood (44mm instead of 34mm) as it provided a fantastic seal. I highly recommend going for 44mm or thicker wood. The walls are solid.

A few minor annoyances I found were that the window only has a standard latch at the bottom, with no handle to lock it further up the window, meaning someone could easily get a crowbar in the top of the window and pop it open. I've bought a few extra locks to secure the window properly.

I've also got to sand a little off the window and door as they catch ever so slightly, nothing too major though.

If you take a look at the photos (on the right of the blog, or directly at flickr by clicking HERE) you can see the photos so far.

At this point the basic shell is complete, the shed is up and painted. Next I'm going to be adding insulation to the floor. I was going to go for 100mm Celotex but the floor isn't thick enough for that, so have opted for 50mm which should still be plenty thick enough. That's arriving tomorrow and once laid I can put the floor boards down and then start work on the stud walls.

To wrap a few points up on the actual shed. It is a Shire Dean Log Cabin at 12ft deep by 8ft wide. I purchased it from Elbec Garden Buildings, but it is also sold by Summer Log Cabins and a few others.

Would I recommend Shire again? Yes, however be prepared to get VERY frustrated with the instructions, and also be prepared to help the delivery driver who seemed a bit flustered (wasn't really his fault, his truck had clearly been overloaded).

Ideally Shire need to work on both the packaging and documentation side of things. There were a number of dents and minor splits. Thankfully I was able to make sure there were on the inside (as they will be covered by the insulation/plasterboard) however I can imagine that there are likely a number of times that the boards arrive badly damaged beyond being usable.

Anyway, in my next post I'll be going through the floor and then the stud walls!

The Base

The base of a log cabin is very important as it has a number of major structural effects. If the load isn't correctly balanced, your cabin may warp or even break. I did a fair amount of research before picking my base.

One thing to note with my build is that I was placing the new log cabin in place of an old shed, which was sat on paving slabs. Today, I broke a hole in the old shed floor to inspect the state of its base. While I wont be laying my cabin on the existing slabs, I needed to see how the ground was. Thankfully it was completely bone dry (surprising considering we've had the wettest few weeks in years!). With this in mind, I can now dismantle the old shed, leaving the ground covered with a tarpaulin sheet until the rain stops and I can lay the new base.

I'll explain in detail what I'm planning to do later in this post, but first, lets talk about the different types of base that can be used for a log cabin or garden office.

Choosing A Base

The first base type is the most obvious: 

Concrete Base

A concrete base is probably the most stable way to set up any shed. If you choose to go for a concrete base, you first need to dig out the land and level it, then place wooden shutter boards around the edge, do measurements throughout to make sure you've got the right size. 

Once your shuttering is in place, lay a damp proof membrane. This will stop anything coming up through the concrete and help to keep it dry. 

You can now lay your concrete. Depending on how heavy your building is will depend on how thick it should be. Realistically most garden office / log cabin structures are fine with 4 inches (10 cm). You can use ready-mixed bags from the likes of Wickes and Homebase if you wish, these work fine. Its usually best to see if you can get a deal on a wet concrete delivery as in some cases it can be cheaper. I personally wasn't able to find a good deal on this for my build when I first started researching.

There are a few important points to note with a concrete base:

• Try not to make your base any bigger than your shed. This encourages water to collect.
• Ideally, you should try and have the base above ground, so it's effectively 4 inches of raised concrete. This does wonders to stop water.
• The concrete can take up to a month to fully set, however in most cases should be fine to build on after 48 hours.
• Concrete actually loves water, so dont be too worried if it rains after you've laid it, it'll only make your base stronger.
• If you are extending an existing concrete base, drill into the sides of the old base and add metal supports, this will help bond the two bases together and prevent them separating.

Wooden Base

I cant stress how much of a bad idea this is if you want your log cabin to last. A wooden base has very little support and will basically be completely rotten within a few years. I'm not going to go into detail on how to erect a wooden base, however I can only say this: dont do it.

Rased Concrete Base

Think about how a pier works, this method works in a similar fashion. You basically create concrete elevated molds (you can buy them ready made) and then place your wooden base on top of these, raising the log cabin up significantly. 

The idea is that you add these concrete blocks under the base, and it created a strong foundation, way off of the ground. 

A very similar method is offered by a few select garden companies that uses metal pads and poles to raise the base.

Plastic Base

Now, this is the method I chose to go with. But before I go into detail, you need to know that there are more than one type of plastic base. There is 'Ecobase' style bases which aren't very thick (between 3 and 6 cm) and a more stable variation called 'HawkLok' or sometimes 'Forest Plastic Base', this is a much thicker, sturdier method where instead of ramming pea shingles into each hold (presumably to hold everything together), the plastic 'pads' each lock into each other, creating a sold, strong pad which acts much like a solid concrete pad. 

When I first looked into this, I immediately dismissed a plastic base as being a bad idea, but the HawkLok style bas is actually pretty clever. It's been tested to apparently support over 28 tons per pad, and can be moved around and reused. For me, it worked out cheaper than a concrete base, and allows me to put it together myself in a matter of hours.

You start by digging out your plot (which is actually optional if you want the shed rased even more). You then place a layer of sand (again, optional but recommended) followed by a damp-proof membrane. You then lay your plastic bads on the membrane and lock them into place, once done you can move it around to get the correct position.

At this point, the base is complete...much quicker and simpler. I'll be doing a full review (and walkthrough) of the base once I get started (assuming the rain actually stops at some point!!)

I had many discussions with members of DIY forums and like myself, many thought the plastic bases were a silly idea and were only intended for small, light sheds, but they work just as well as a concrete base, and theoretically should be even better as they allow for a bit more air circulation, shouldn't get anywhere near as cold as concrete does, and can be reused. Only time will tell just how good they are though!

Choosing a Log Cabin

I spent a LOT of time researching which log cabin I wanted. The biggest issue I found was getting answers to a few critical questions:

1) How thick is the wood used?
2) Does the thickness of the wood really make that much of a difference?
3) What kind of windows and doors do I need?
4) What sort of insulation do I need?
5) Will this be way too cold to use in the winter?

I joined several DIY forums including DIYBanter and DIYNot. I got some awesome advice from people on there who were a lot more experienced than I was (the most DIY I've ever done is fixing a bedroom door that wouldn't close!) who were able to point me in the right direction.

Picking The Log Thickness

I opted for a 44mm wood. Whilst I've seen some others get away with 28mm, I wanted the extra thickness as you get an extra groove out of the wood. Take a look at the picture below and you'll see what I mean.

If you look at this picture, you'll see that the 28mm and 34mm wood, only has a single tongue and groove system, whereas the 44mm and 70mm have a double T&G system. This not only makes the wood stronger, as it locks together better, but also adds an extra water barrier, and basically provides a better outer insulation layer.

Initially I looked at a 28mm cabin from Tiger Log Cabins, however ended up opting for a Shire Dean Log Cabin from Elbec Garden Buildings (also sold by Summer Log Cabins). This allowed me to go for the 44mm wood.

Windows & Doors

Since this room is going to be used as an office, I need it to be relatively secure. Generally sheds (and even log cabins) come with either plexiglass/plastic or single layer glass windows. This really wasn't going to be secure enough. The same usually happens with the door. You generally get a thin, flimsy wooden door that really is next to useless if you plan on using the building as anything other than a shed.

As I mentioned above, I chose a Shire Dean Log Cabin. The great thing I found about this model is that you can have double glazed windows and doors. Thats not to say that this is the only model that offers this. Tiger Log Cabins offers it across most of their cabins, and a number of cabins from Dunster House and Garden Buildings Direct also offer full double glazing.

Ultimately you should go for Double Glazing (or toughened double glazing if offered) and it'll not only improve security but also insulation.

I'll be covering the base and insulation in my next post so stay tuned!