Sunrooms: Steel Frame and Wall details.

CorkHarbour

Hello All,

I'm trying to design a sunroom extenstion to my home.
It will be a 3.5 x 4.1 four season sunroom, with a fully slated hip roof with three fixed skylights. It will have one solid wall on my closest neghbours side and the gable end and return wall on the other side will be mostly windows and a set of french doors.

I am wondering if anyone here has built a sunroom with a steel frame themselves?

I would love to know what path you took in the fabrication of the steel frame that supports your roof. did you go the welding or bolted frame route?

What kind of wall structure did you put in place etc.?

As much detail as you would like to share, I would really appreciate knowing.

If you had any links, drawings or info I would love to hear them.

beyondpassive

How do you prevent the steel from being a cold bridge. You'll have a lot of water condensing on the frame?

CorkHarbour

Thats just one of the many questions that I have my self, I presume i'll have to insulate the frame but its very hard to find images of these structure been built, and they are really common it seems, just nobody knows how its done it seems.

The frame will be <SNIP> box steel galvinised , I'm going to anchor bolt it to the foundations, that would seem better to me than going and burying a steel member in concrete all by myself.

I'll bolt the frame together as I'll want to keep the galvinised skin complete to prevent rust setting in.

I have no real idea yet how all of this will be acheived.

I'm thinking that I might use a Roadstone type 45 block in the structure seeing as the frame will be the load bearing member not the brick work.

All answer on a postcard please lol.

Mod Edit: I've removed the size of the steel section above as we do not specify structural elements on this forum. Please read the charter. The steel sizes should be determined by a structural engineer and will obviously be determined by spans, loads, etc.

martin46585

have a look at http//www.keystone-lintels.co.uk/sun_lounge_lintels/index.cfm which also gives some drawing details

CorkHarbour

That is simply an outstanding linky, thank you martin46585 some great info there, cheers kid!

Poor Uncle Tom

Any steel frames I've seen or used, have been where the amount of supporting blockwork is at a minimum (lots of glazing) and where the internal roof space is being exposed.

The frames are made up of stanchions bolted to the foundation and usually welded to the top plate. These are usually a mixture of galvanised steelwork and primered and rustproofed at the weld joints. The stanchions are usually positioned inside the cavity, surrounded with a dpc. Once the stanchions clear the cills they are incorporated into the window sections using slieves of uPVC.

CorkHarbour

Mad question I know tom, but the uPVC sleeves are added after everything else roof etc. when the windows are going in right?

Are the windows just drilled into the steel up pillars at the wall sides and the corners? Or do you have to pre drill the pillars to accept them?

I will have one solid wall and mostly glazed the rest of the way. What type of wall detail would you normal have used?

The lintel link is very close to the designs I had in my own head and I can fabricate them myself from steel as I wasnt thinking about having a course of blocks above the windows or should I seeing as I am going to use a hip roof design.

Would you normally use a steel ridge beam with these type of sunrooms Tom?

Poor Uncle Tom

CorkHarbour wrote: »

Mad question I know tom, but the uPVC sleeves are added after everything else roof etc. when the windows are going in right?

That's mostly the way I've seen it done, however I put a feature window in my own house 10 years ago and I used a central steel pipe 8 m long and I got the sleve put on at the start.

CorkHarbour wrote: »

Are the windows just drilled into the steel up pillars at the wall sides and the corners? Or do you have to pre drill the pillars to accept them?

The steel pillars are not pre-drilled, there is a filler piece which takes up the shape of the pillar attached to it and the window frame is usually attached to this with a cover strip on the joint.

CorkHarbour wrote: »

I will have one solid wall and mostly glazed the rest of the way. What type of wall detail would you normal have used?

I would not put a steel at the wall, I would let the solid wall carry the load and detail the window to wall joint with insulations and DPC's as normal.

CorkHarbour wrote: »

The lintel link is very close to the designs I had in my own head and I can fabricate them myself from steel as I wasnt thinking about having a course of blocks above the windows or should I seeing as I am going to use a hip roof design.

The one in the link looks fine, but remember, If there's blockwork going over the heads the steelwork becomes far bulkier to take the loads.

CorkHarbour wrote: »

Would you normally use a steel ridge beam with these type of sunrooms Tom?

No, the spans are usually very small, and no real need for a steel ridge, but you engineer would need to answer that definitely for you.

imitation

Steel frames used in my house (Which has just been done) are welded at the joints and bolted to block on edge (I think, id nearly have to look again) sitting on the foundation. Where required studs are also welded to the top of steels.

The builder painted the steel in rust proof paint. The one thing Im wondering about is where its bolted down, as he didnt paint the base of the steel.

The other thing to watch out for is cold bridging, if there is no coating on the steel between inside and out then it will be a condensation point and you'll get water ruining your window boards. The main way around it seems to be a cladding for the steel.

CorkHarbour

The builder painted the steel in rust proof paint. The one thing Im wondering about is where its bolted down, as he didnt paint the base of the steel.

He should really have paint the whole thing prior to going down, this would be standard in the marine industry where i work butI'm not to sure about civil construction but corrosion is corrosion.

I would not put a steel at the wall, I would let the solid wall carry the load and detail the window to wall joint with insulations and DPC's as normal.

I am leaning this way as well, the keystone type lintel may be theitem to make my build so much more efficent.

By wall detail I meant I was thinking about 100mm block on edge, 20 air gap, 80 insul, 100mm block on edge with insul cavity closer etc.

but remember, If there's blockwork going over the heads the steelwork becomes far bulkier to take the loads.

I'll be going for the very minimum block overhead required to carry a hipped roof, I'm hoping single course of block overhead with the bottom of that block starting around 2.20m of the floor level and the roof topping out at 3.5m max as the windows cills on the 2nd floor are 3.6m.

that gives me a hip roof of 30 degree pitch approx over a floor area of 4.1 x 3.5 max outer walls.

dathi

dont forget to insulate the original block wall that is between your house and the sun room on the sun room side with insulated plasterboard as this wall will become one large thermal bridge if you dont also if you are putting in heating make sure that you can isolate the heating in the sun room from the rest of the house