Steven Briggs wrote:
I'll be building from scratch, as I want a challenge and to achieve
something better, more substantial and different from the usual stuff.
That sounds familiar - played the same game myself a couple of years ago...
It'll be about 18' x 8', part potting shed, part summer house, with
covered veranda deck area. There's a CAD render of the design at
http://www.sbriggs.plus.com/shed14.jpg
Oh very posh ;-) Mine was a bit simpler:-
http://www.internode.ltd.uk/workshop/plans.htm
I have a few questions for the collective wisdom of the group on
construction methods and materials.
Fire away...
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.
I did similar - 50x100 floor beams at about 500mm centres on a matrix of
half bricks set level on the concrete base. I used 19mm ply for the
floor which worked very well.
Wall & roof framing I'm thinking 25x75 sawn timber studs & rafters,
50x75 for the framing will give a really solid frame and a bit more
space to play with for insulating and adding electrics etc if required.
50x75 sill & head. Inside skinned with 6mm WBP ply, outside with VT&G
50x100 ridge beam, 19mm shiplap cladding, 12mm WBP ply on the inside -
as Andy suggests it is nice and easy to fix things to after.
weatherboard. 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? Should I put a vapour barrier in there somewhere? If so,
what to use?
Not suggesting this is the best way - but I went for 50mm jabfloor
(cheaper than celotex - but not quite as good - so your 30mm will
probably be as good or better). I fitted it flush with the outside of
the framing so that it formed a vapour barrier next to the shiplap -
that then left 25mm of space inside the warm/dry area for all the
electrics I wanted installed in/under the interior ply.
Timber treatment is another issue. While the floor joists will be
tanalised timber, I don't think my local timber yard has on-site
treatment plant, so everything else (weatherboarding, frame, floor etc)
will be untreated red or white wood. I could then paint or spray a
suitable preservative on, but would it really be worth shopping round
and getting the whole lot prevac treated (which adds about 20% to the
cost)?
Bog standard sawn kiln dried timber is nicer to work with and cheaper -
just give it a few good coats of cuprinol first.
(as an aside, using a low pressure "pump up" sprayer is a quick way of
doing the job without loosing as much cuprinol as you will with the
finer atomisation you get with a spray gun on the compressor - really it
needs soaking more than it needs a fine finish. I originally did my one
with a brush which took ages - got a pump up sprayer from Wicks the
other day for about 13 quid, that let me re-spray the whole thing in
about an hour)
Any other construction or material suggestions welcome.
In no particular order:
Good three layers of felt on top of at least 12mm WBP ply.
Leave a little air gap underneath the whole shed so that it stays
ventilated.
Give the floor beams and the underside of the floor a good soaking in
wood preserver since you will not be seeing them again for a long time.
Get a decent respirator if spraying cuprinol (the 15 quid 3M jobbies
from Screwfix work well and will also block the smell of the stuff
completely)
Stick some diagonal cross braces in the wall stud work as it will make
the whole thing much more rigid and will prevent any of the framing
leaning or skewing. I ended up using only half the amount that you see
on the drawings - as that seemed to be enough - but doing some is well
worth it. While on the topic, stick a couple of cross braces between
some of the rafters - this will convert the load of the roof (and anyone
on it!) into a downward thrust rather than a "splaying" thrust that
would otherwise tend to push the walls out. Note also three layers of
roofing felt is heavy!
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?
My tools / materials shopping list was:-
http://www.internode.ltd.uk/workshop/tips.htm
18g are a bit on the light side - having said that - they are what I
used. I used 30mm brads which are cheap enough you can afford to use
loads. Hence I stuck between three and five into the lower quarter of
each plank every time it crossed a joist. It has been up a couple of
years now and seems to be holding tight - although it is in a reasonably
sheltered location.
Anyway if you want the whole saga you can read it he-
http://www.internode.ltd.uk/workshop/
--
Cheers,
John.
/================================================== ===============\
| Internode Ltd -
http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/