On Fri, 9 Apr 2004 21:58:31 +0100, Steven Briggs
wrote:
The latest thinking on the base is to mount it on single brick pads (on
a large, existing concrete platform), then a 50x100 joist frame, T&G
floor, then the shed structure.
With this, I wouldn't go for more than 450mm centres.
You will need a matrix of brick piers.
That is the plan.
OK. For this, I wouldn't go for a distance between piers of more
than a metre, otherwise the floor is going to be very bouncy.
That's going to be a lot of piers (around 15-20). If the existing
base is reasonable, I would rethink the timber bearers idea.
Also, it's useful to make a complete frame with the floor joists with
timbers across the ends. Then you can make a skirt of TGV cladding
and take it almost to the concrete.
Alternatively, what I did was to start with a concrete base and then
use pressure treated wooden bearers on it and the joists orthogonally
on top of that. It's worth putting some DPC material like Visqueen
down to isolate the timbers from the concrete. You can also use
packing pieces on top of the bearers in order to level the final
floor.
Wall & roof framing I'm thinking 25x75 sawn timber studs & rafters,
I'd up that to 50x75mm for good strength.
50x75 sill & head. Inside skinned with 6mm WBP ply,
I would go for 12mm or even 18mm there because you can fix things to
it. 18mm ply is used in large quantities (or OSB as an alternative)
so it is not that expensive. You will get a much sturdier result.
outside with VT&G
weatherboard.
That's fine.
I'll put about 30mm of Celotex / Kingspan on the inside
face of the wall cavity. I'm debating the need to vent the remaining
cavity to the outside, I can easily have a 10mm hidden gap around the
framing at ground & eaves level, and over the roof ridge board. Is this
a good idea?
Yes. What I did was to tack nail small spacers to the sides of the
vertical studs such that the Celotex front face was level with the
front of the studs. Then I tape sealed the Celotex to the studs with
metallised tape and ply clad on top of that. This created an air
gap behind and ventilation was arranged to the air gap.
Ah, good idea.
It would also be worth insulating the floor and ceiling.
They will be.
You might want to think about two glass panels for the windows and
doors or even find an inexpensive source of double glazing inserts.
This will make a big difference. With single sheet glass you are
going to lose a lot of heat. Another option might be secondary
double glazing inside.
For the floor, build the floor frame and then tack nail spacers in
the same way as I described for the walls. Drop in the Celotex and
put flooring on top of that. I used 18mm T&G for that.
it is also worth insulating the roof. I used exactly the same
technique for that, making sure that there is ventilation on the cold
side.
Yep. Ventilation from eaves, and a small gap over the top of the ridge
board.
I made a ridge cap out of Western Red Cedar and spaced it off from
the roof. There were ventilation strips set into the top of the
ridge underneath the cap.
This means that air is drawn in under the eaves into the space above
the insulation and out at the ridge.
Finally, this is grand excuse for compressor and nail gun purchase.
Probably the Axminster £100 compressor (2.5HP /25L /7cfm FAD) and 50mm
brad nailer. Are 18ga brads going to adequate for the cladding?
Not really. I used 16 gauge. 18 gauge is normally used to hold
things together for gluing, not for fixing. You need a nailer that
takes 16ga finish nails.
Yeah, I thought it a little mean for the job too. But 16ga nailers are
way more expensive (£175 vs £45). I'll have to see what's in the piggy
bank.
18 ga really is not going to do a good job of holding the boards.
The time saving of a nailer on a job like this is enormous so it is
worth the investment.
Rutlands (
www.rutlands.co.uk) have a 16ga nailer for £150.
Top Gun Air Nailers (
www.topgun.co.uk) have a Porter Cable for £150
plus VAT (£176).
I have several Porter Cable nailers of different sizes including this
one. Porter Cable and Senco are the two leading makes and this is a
good deal.
I have also found Top Gun to be really good and helpful on obtaining
nails at pretty good prices.
For example, I used cedar shakes for the roof of the cabin that I
built last year.
http://www.johnbrash.co.uk/shakes.shtml
These cannot be fixed with galvanised nails because the tannin in the
cedar corrodes them, so stainless steel was needed. Not easy to get
but Top Gun managed to source and supply some.
Thanks Andy.
Now back to the CAD drawing. Doing a detailed frame design now. Next
challenge is to draw the valley rafters.
http://www.sbriggs.plus.com/shedv305.jpg
is this afternoons efforts.
If you need some help in the detail of the studs and rafters, there is
a good plan for the construction of a shed at
http://www.plansnow.com/shed.html which can be downloaded for $9.50.
This uses more or less exactly the construction that you have
described and goes into how to correctly joint and notch the framing.
..andy
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