Self-build summerhouse / office / playhouse?

With JB's method for constructing the base, I believe the walls would be open. If the underside were open for air to circulate freely then no a dpm wouldn't be much use.
I was describing what I would do were there a continuous perimeter wall of blocks/bricks. My presumption causing confusion, sorry there.

The cls does come in 8 or 10ft lengths (2.4 or 3m) Most places only do them in 2.4. Height is up to you, a standard door in a house is about 6'6", 2 metres-ish. I'd consider a minimum height of 2.2m but you can go all the way to 2.4 if you want it to feel nice and spacious inside.

Distance between studs should be at maximum 600mm, 450mm will be be better though. At least one row of noggins down the centre, the height of which should be the same height as the type of insulation you are using, rockwool type come in at 1200mm high, rigid boards usually come in big sheets which will need cutting to size regardless of noggin height.

You will need to temporarily brace the frame work with a long 4x2 diagonally on the inside, to keep it all square before you add the outer boards/cladding.

The ply/osb on the outside isn't strictly necessary, but better for rigidity when building, and security if that will be an factor. 11mm OSB will do the job just fine, you'll get away with 9mm ply if cost is an issue.

You can put it on the inside, under the plasterboard, if you wish.

Breather paper is brown 'wrapping paper' with a waterproof coating, breathable roofing felt would do the same job, only better.

Rockwool slab is fine for the insulation, you will get better performance from celotex/kingspan but at a higher price.

Only use pre-treated timber for the base, the cls should all get a coat of clear wood preserver before construction, although many builders wouldn't bother as it's not overly important if it's built correctly.

Roof should go before insulation or flooring, you can work on a ply temp floor while you are putting the walls up.

Low pitch ok, but fitting a skylight will be tricky at low pitch, I'd be tempted to get a sheet of polycarbonate for a section of the roof, which continues all the way down to the edge of the roof. Or a roof dome of some kind.

B&Q warehouse's are a good cheap source for the CLS BTW

As far as height goes and to save a lot of cutting I would make the tall long wall 2378mm high (2300+38+38) and the shorter wall which I assume will be on the fence side about 100mm shorter. This means you only have to chop 100mm/200 off all the verticals on one side and saves having the hastle of furring pieces to get the slope, the roof timbers can just be set on the two different height walls to get the fall. I would set the studs at 400mm(note plasterboard is 1200wide but the ply is 1220) so better to set out to suit the plasterboard

Shuttering ply or OSB will be fine for the outside, it makes the whole structure rigid.

Building paper as Deluks mentioned wil not breath as well as a whapping membrain but should be OK, I would go with something like Tyvek but again depends on cost

For insulation you could use 100mm rolls of fibreglass as used for lofts, 75mm thick polystyrene or 70mm kingspan/celotex. The price goes up as the insulation values go up.

The same DPM is fine as is the plasterboard.

Put the rof on before any fibreglass or plasterboard.

Have a look at this thread where the guy has drawn the frame and also look at the site I linked to.

//www.diynot.com/forums/viewtopic.php?t=126990

Jason

Thank you guys.

Jason Thank you for the album post its good to see how others have done it. I wish there were a few more detailed pics showing how exactly he did things, roof / corners spring to mind . I like the way he did his foundations. Just wondering if this is easier to do for my build? Mainly because I thick obviously as I am unable to work out how I use the water level I brought to make sure the concrete levels in each foundation strip is the same height! (unless I'm again being thick I can't see how the water level would work when the concrete levels are below ground level). Using the technique in the link you gave I only need to make sure the level of the pile shuttering is level and all should be fine.

*** EDIT *** I was being thick as you have already explained how to make each foundation strip level! Would the pad/pile foundation technique be a better solution? no need to lay blocks. ***

Also I like the way he kept the floor insulation in. Its the way you first described to me if I'm correct but as you mentioned very time consuming. Wondered if there is a quicker way to have nearly the same effect? unfortunately I don't think I would be able to put boards onto the joists then turn it over and I don't know anyone who wears his underpants on the outside and has a big S on his chest who could do it for me .

Why are furring pieces hassle?

I've been looking at http://www.buildeazy.com/plans/helpfiles_wallframes.html can you see any problems with how this details what should be done?

Any tips on how I do the roof next . I wish to have insulation in this to, would like if possible some light through it but if not no problem.

Still waiting for the builders to finish the work on my house then I can get started on this project.

Thank you for all the help.

All the best.
Michael.

Easiest way with the water level is to fix each end to a length of wood say 1000mm long, you can then rest this on top of the leveling pegs and the water won't run out.

Furrings are long tapered pieces of timber that sit ontop of level joists to give the roof a slope, if you want the inside ceiling level then you will need to use them. If a sloping ceiling is acceptable then just let the joists slope, not what you would do on a house but OK for this type of thing.

Pad/piers would also be OK for you to use. Four rows of three piers, in otherwords each strip is replaced with one pier at each end and one in the middle. You can then bolt two 6x2s together and use jiffy hangers to support the joists from these.

Let us know what type of floor insulation you are going to use and will suggest a way to support it.

The link to the wall framing is OK but you don't need the extra understuds and just a single stud over openings will be fine for the likely loads.

For the roof 150x50 timbers at 600 cts wil do with 18mm WBP ply on top then felt. Fibreglass insulation will just push in between the joists (buy the 1200/600 rolls) and 9.5 TE plasterboard.

You can make a simple upstand and then felt over this and fit a dome to the top or buy an upstand with opening dome http://www.loftshop.co.uk/products_detail.asp?catID=2&typeID=8&pID=68

Jason

Thank you.

I knew what furrings were as I had read about them recently I was just wondering why you thought them a hassle? I thought they would be easier.

I like the idea of a flat ceiling but obviously this then makes the idea of a skylight a little more difficult. Although with the prices from the link you posted I may not bother. Can't believe a bit of polycarbonate can cost so much and that's without the frame! (not sure I could make the upstand and opening ones would probably be preferred).

Still haven't decided on the actual materials e.g. insulation as I am still making sure I know how I'm building it. Levelled and marked out the area today. Will be digging the footings out tomorrow (as its now nearly 2am - it should read today!).

I notice on the other thread you mention cast in 2 parts, 1st 600mm x 600mm x 150mm @ a depth of 600mm (top being 450mm below ground level?). Followed by a 2nd section 300x300 x height required. Minimum 100mm above ground level? Mix 4/1 or 3/1? 4 rows of 3 which to be spaced evenly would require 2400mm ground between each along length and 825mm ground between each on width (at sizes marked today**).

Does this sound like overkill for the footings?

Then DPC, 2x6x2 bolted together (get to what fixings etc. recommended later) around the entire perimeter **. Then joists (6x2) @ 400 ctrs across the width, also some sort of insulation between joists & noggins (2 per length, just over 1 metre apart?) + whatever to hold / fix it in place). DPM. Ply floor.

** Talking of perimeter, the area marked out today was roughly 3450mm x 9600mm (just over 11ft by nearly 31.5ft), this is to the outside edge of the pads so the floor will come in by 1/2ft all round - if I'm correct).

I notice in the photo album you posted the link for, that they covered the ground in stones / pebbles of some description. I assume this is to prevent weed / plant growth. I am certain to need to prevent this to as it comes from all angles at the rear of my garden. Was thinking of laying some kind of membrane maybe before casting the 2nd tier of the footings to hold it in place and then covering with stones or is there a better cheaper way?

Anyone use these before? http://www.buildingsuppliesrus.co.uk/sections.asp?id=5693&aid=&aguid=&b=&guid=
any good?

I think this could get expensive!

I notice on the other thread you mention cast in 2 parts, 1st 600mm x 600mm x 150mm @ a depth of 600mm (top being 450mm below ground level?). Followed by a 2nd section 300x300 x height required. Minimum 100mm above ground level? Mix 4/1 or 3/1? 4 rows of 3 which to be spaced evenly would require 2400mm ground between each along length and 825mm ground between each on width (at sizes marked today**).

Pad and separate pier is a better way to go, the wider pad spreads the load, the thinner pier saves concrete.

Mix 1:6 cement:balast

825mm how did you get this size. the centers should be about 1700mm

Then DPC, 2x6x2 bolted together (get to what fixings etc. recommended later) around the entire perimeter

No need to do the two long edges, just a doubled up pair where each strip would have run, then hang joists between these, end joist will act as perimeter.

That supplier looks expensive, £27 for a sheet of MDF, I can get a decent brand for half that.

Jason

My posts keep disappearing!

I worked the 825mm out as follows:

0 - 600mm 1st pad
600-1425mm ground
1425-2025mm 2nd (middle) pad
2025-2850mm ground
2850-3450mm 3rd pad

1425mm centres, assuming centre of 1st pad to centre of next pad is how you work that out.

Can you confirm that the pad is supposed to be dug to a depth 600mm? So far dug 5 holes 600mmx600mmx450mm (clay is hard to dig into!).

Mix 1:6, is this strong enough for pad and pier?

Does the pier have to be placed centred on pad? Just the ones on the right hand side (nearest to path) I would prefer to be placed as far to the right as possible.

Thank you.
Michael.

We've dug the 12 holes:

http://www.always24-7.co.uk/diy/holes_dug.jpg

The only hole that seems to be a problem is this one:
http://www.always24-7.co.uk/diy/hole.jpg

This one half filled up with water over night and didn't soak away, the photo was taken after I bucketed the water out. Only added the photo here in case it could possibly cause any problems.

I now plan to fill the bottom 150mm of the holes with concrete, the holes are roughly 60x60. I then plan to make up some shuttering roughly 45mmx45mmx400mm which brings the foundations up out of the ground by 100mm at the highest point (rear of the pic). How much cement / ballast would I require to do the 150mm plates and the piers? Best place to buy at the moment? Also need plywood for the shuttering what size is the best to go for (cheapest being better obviously) or OSB?

What should I do regarding a membrane of sorts to prevent weed growth etc.?

All the best.
Michael.

When you come to pour the foundations dig out any of the wet clay from the bottom of the damp hole so the concrete is going onto firm clay.

With the loadings on the foundations the risk of them tipping due to rotational forces from an off set load is small so you could off set the pier. Though it would be OK to put the piers central and let the doubled up joists project beyond the pier by 75mm or so.

You will need 0.65m3 conc for the pads if the holes are spot on but they usually work out a bit oversize and 0.98m3 for the piers. So a total of 1.63m3 of concrete which will require about 2.6 tonne of balast and 433kg of cement. Go to a decent builders merchants for these, loose balast is cheapest followed by the bulk bags with sacks being the most expensive. It would also be worth costing one of the concrete firms that mix and place the concrete, try yellow pages.

Shuttering ply also from the builders merchants or timber merchant will be better than OSB and not as costly as WBP ply. If you do mix yourself you will not need to cast in one go so could make up say 3 shutters and reuse them.

You could cover with a heavy black polythene or one of the membrains from a garden center to keep the weeds down.

Jason

With being able to have the pier off centre and possibly having the joists project beyond the pier I could use 300mmx300mm piers (I noticed I wrote 45mm in my previous post, I meant 450mm or 45cm).

Regarding the membrane, should I cut it around the piers? If so hold it down how? Cover the entire ground up and over the piers (doubled up joists holding it down)?

Thank you.
Michael.

Called Selco to enquire about a cash account, explained I wasn't a trader and they said yes I can have an account. All I need is a Makro card as proof as that is only available to traders to! Rest of the conversation didn't make much sense either. However I do have a mate who's wife has a Makro card so should be able to get into Selco! .

Where is the best place to buy the cement / ballast and shuttering ply? And hire a cement mixer?

Thank you.

I'm after building something in my back garden. I've been told whatever it is, irespect of where, size shape.... It will require building regs Part-P if I want to run power to it . This came into effect 2006 and uses new coloured cables etc, just thought I'd mention it.