Rebuilding Conservatory - roofing question

[sh4d0w]

Hey all,

I am going to be replacing the roof, windows and french door on my 100BC Conservatory soon, i have a brick dwarf wall with no cavity (that i can see).

My Plans are... to use the existing wall but kingspan the inside, move the door up to one side but using the existing footings, i have dug down and they are 22-24" deep. I then want to replace all the windows and roof, the roof i will keep as a lean too of the back of the house but build it off with timber, the conny is 4mtr x 6mtr. i want to two velux and ill tile the roof to match the rest of the house.

Questions.
1) I was planning on using 6x2 for the roof but figure i best do the calculations properly, can anyone point me in the right direction for this?

2) If i am rebuilding part of the dwarf wall, would it be a better idea to knock it all down and rebuild with a cavity to avoid kingspan/celotex on inside?

3) and most importantly for me.... At the minute the roof is just sat on a 3x3 timber wall plate sat straight ontop of the frames, from what i can see there are no steel uprights in the frame. the new roof will bare a hell of a lot more weight with the timber, tiles and windows... How best to support the new roof?
A) RSJ over windows
B) Wall plate sat ontop of new frames, can see this causing big problems for shape and maybe even window cracking
C)build some brick pillars and sit on timber

Obviously coming off the house ill fix a timber to the wall and come off that, no point in removing bricks to sit in.

Thanks all

 

[sh4d0w]

Ofcourse!... ill be using Shingles on the roof, not tiles. so the weight will be FAR less.

 

[theprinceofdarkness]

So exactly what is your roof/ceiling construction?, sounds like shingles (to match house roof?), then lathes, then sarking cloth. With a couple of Veluxs, all sitting on 6" X 2" rafters at 4m+ long. So what about insulation, VCL and plasterboard?
6m is a long way, and it would be nice to support the wall plate/RSJ every side of a window frame. So splitting up the unsupported distance to 1m chunks. it will make the wallplate/RSJ very much smaller. You have not said what sort of window frames you will be using. If UPVC then I think you should use the propriety steel supports for the frames. if they are going to be home brew then I think the way I would do it is :- Use 4" X 2" PAR, trench both side of the 4" dimension to a depth of 3/4"by 1 1/2" wide. This is so the glazing fits into the trenching and can be fixed to the upright withe triangular beading. The excess depth of the frame I think should stick into the room. Most of the time you will be looking at the window straight on, and so looking at the upright edge on.
Frank

 

[sh4d0w]

Thank you for your reply Frank!

Ok, so my current construction is uPVC as can be seen in attached photo (poor one at that)

The new roof i have in mind:
Timber wall plate bolted to the existing house wall.
Timber rafters to either a timber wall plate if can sit onto of frame or to an RSJ
Kingspan or Celotex 70/100MM insulation for between rafters at 500ish centers
Two Velux windows - not sure on sizes yet
And to save on cost and weight shingles to match house tiles - best i can find.

As can be seen in the photo i want to move the door over to the right side of the room to maximize usability of the room


I was hoping to use the existing wall to the left and also run at the same pitch as too keep in check with the kitchen to the right.

and roof construction similar to this, minus the ceiling joists

 

[theprinceofdarkness]

Still confused, "shingle" as far as I know are split bits of cedar wood, often used over the pond cos' wood is cheap. I think you have ordinary clay tiles. I would Google around to find the minimum pitch for these sorts of tiles, I think that your pitch is too low.
Frank

 

[sh4d0w]

better photo

 

[sh4d0w]

Hi again,

yes the pitch is too low for the tiles i have on the roof as it is.

I am referring too man made synthetic slates similar to
https://www.roofingsuperstore.co.uk/product/tapco-synthetic-slate-pewter-grey-704.html

 

[sh4d0w]

Guys, can you advise, I am going with a man made lightweight tile system from Decra, the construction i have in mind will be this, Outside down:
Decra Statos Tiles, 38x50 or 25x50 laths, breathable membrane, 6x2 rafters at 450 or 600 centers, I have been all for 450's but i now think 600s will be adequate, then 100MM foilbacked celotex between rafters flush to face of timber not membrane so the void is between the membrane and insulation, then plasterboard, i was under the impression i wouldnt need a VCL but can anyone clarity?

Martin

 

[theprinceofdarkness]

VCLs cost peanuts, and help to stop moisture finding its way through tiny little holes between your celotex and the joists. You may regret not spending the tenner in 5 years time.
Frank

 

[sh4d0w]

Ya see Frank, this is why i am asking, i dont knot the answer or the uses/duties of a VCL like i should,

can you perhaps point me in the direction of a product to use?

what about 100mm between rafters then some 40mm fixed to the rafters foil taped to seal, will this act as a VCL? and also add an extra layer of insulation