Small Extension mainly glass construction

[andy100]

We have a traditional 3 Bed semi, the kitchen being an add on to the rear of the building leaving a space to the side of the kitchen that I would like utilise.

The extension is to the rear of the property not visible from the front, is to have a tiled roof which is a continuation of the existing kitchen roof using the same tiles with two large roof windows installed, I intend fitting a matching window to the kitchen roof also.

The front of the extension is to be glass with two French doors and glass opening windows floor to ceiling either side.

For simplicity I intend having a steel framework resting on suitable foundations taking the weight of the roof.
Question 1 What foundations would I need to put in, the vast majority of the weight would be from the roof.
Question 2 How do you fix UPVC frames to a steel structure I'm assuming if its a steel box section I could use UPVC self tapping bolts.
Question 3 Is it permissible to weld the structure together.
And last Question What size wooden roof supports would you suggest for a 3.7m length 6x2 or 4x3.
Many thanks for your help as I'm getting nagged by the wife to start this project.

 

[Leofric]

Are you having any drawings prepared for building regulations approval which would answer some of your queries as well as provide other necessary construction information

 

[noseall]

Question 1 What foundations would I need to put in, the vast majority of the weight would be from the roof.

The same as any other foundation, i.e. 1m deep etc.

Question 2 How do you fix UPVC frames to a steel structure I'm assuming if its a steel box section I could use UPVC self tapping bolts.

Yes, tec screws, bay-pole screws or self drilling screws will be ok.

Question 3 Is it permissible to weld the structure together.

Possibly, but that is a design question and will be down to the SE. One of the problems with welding is the process itself can cause torsion and twist as the items are welded together. I don't know which is preferred - welding or bolting.

And last Question What size wooden roof supports would you suggest for a 3.7m length 6x2 or 4x3.
Many thanks for your help as I'm getting nagged by the wife to start this project.

6" minimum deep timber is standard (for vaulted roofs) to accommodate the 100mm Celotex plus air gap.

Don't forget the 25% glazing rule.​

 

[Leofric]

Another point (by no means all ) cold bridging needs to be considered in an external wall steel structure. Correct detailing required.

 

[Leofric]

Don't forget the 25% glazing rule.

and other things

 

[andy100]

Many thanks for taking the time to answer my many quires.
After reading another thread, they had asked the buildings inspector to come and advice before starting the build, I thought good idea only to get an email back saying this service is not provided in Trafford.
So I guise I will have to get some plans drawn up.

Cheers Andy

 

[cdbe]

Surely you just want a cavity wall down the right hand side with a small end return for stability and utilise existing kitchen wall on left. Lintel or steel across front with uPVC or aluminium windows/doors below?

 

[andy100]

That was my original plan as I'd rather not work with a steel structure, but it was pointed out to me the wall at the end of the kitchen was originally a utility room so might not have substantial foundation. But I would assume the house would have the same foundations throughout.

 

[^woody^]

only to get an email back saying this service is not provided in Trafford.

It's not provided anywhere. It's an inspection service not a design service.

 

[Notch7]

My initial ponderings:

-you prob cant continue the pitched roof as its over 3 metres high at the rear -needs planning but questionable whether you get perm
And its more than 3 metre projection on semi detached house.-needs neighbour consultation.

In regards to the construction, I guess the RH wall is to be brickwork -in which case you might as well want a 335mm return at front.
Previous jobs Ive done have used a 150 x 150 x 15 equal angle cast into the found and go in the cavity in the corner.
That acts as a cantilever windpost, avoiding the need for a buttress brick return.
LH could have a steel post. -maybe you need 335mm brickwork this side to hide steel, then windows will be between a brick opening, better than a 100mm plastic trim on left to hide steel post.
Just a bit of guesswork -it needs a SE
Maybe your existing extension will act as buttress......

In principle though its a goal post of sorts you need.
It needs detailing to avoid bridging and it needs to be positioned to have a wall plate on top for the rafters.

 

[Leofric]

I will have to get some plans drawn up.

Correct answer