Insulating Steel Beams: how best?

[ToughButterCup]

@MrsRA loves gardening. And that's why we chose a design which incorporated a Winter Garden inside the house. It is an unheated area on south west corner.

The Winter Garden extends from floor level to the roof and so it needs steels to hold it in place. Those steels need to be insulated. A quick look at how we could get that insulation done threw up many types of insulation, and many methods of incorporating the insulation on the steel

 

 

I bet someone here has done this before, and can offer advice. Please!

Ian

 

[warby]

I have borrowed this info from others over the years: "Fire Protection - We have insulated the steels in different ways depending on available space. Where there's enough space we have insulated the beam with celotex along the sides and underneath and then built a timber box which we've clad with a single sheet of red fire rated plaster board. Could you drop timbers down the wall above to make the box, with the bottom of the box suspended the uprights?
Where space was tight in terms of ceiling height, we used either Aerogel at 30 mm and added fire rated plasterboard beneath. We also used intumescent paint on part of the structure which allowed us to incorporate the beam into the wall without a separate fire rated box.
I guess that you'll expose the beam, but if you apply the fire rated plaster board tightly to the bottom of the steel you would be able to insulate beneath the plaster board and the timber beam fix ordinary plasterboard to a baton at the top of the sides of the timber beam. The BCO was more than happy with all our "solutions" even if we did , in his opinion, overdo the amount of insulation!
. -Jotun Steelmaster 60WB is a water based intumescent coatings for structural steel, supplied in a thick paint which can be applied by brush, roller or spray to provide up to one hour fire protection to most structural steel sizes. In the event of a fire the intumescent coating expands to insulate the structural steel from the fire. Benefits Tested to BS476 Part 20/21. http://www.paints4trade.com/jotun-steelmaster-60wb-water-based-intumescent-fire-proof-paint-3959-p.asp. One of the critical elements of a passive house is not to have thermal bridging of the insulated layer. All steel work is kept to the inside leaf of the frame, allowing good coverage of insulation around steel and keeping it on the warm side of the build."

Edited January 2, 2017 by warby

[ToughButterCup]

@warby, thank you very much indeed. Lots to go on here. 

Ian

[TerryE]

Ian, isn't your Wintergarden unheated and entirely outside your temperature controlled living environment?  Looking at the drawings it looks like you've got steel verticals carrying the horizontal steel members, and these are effectively external structural members.  So why do they need insulated?  Even if these are close coupled to the blockwork, then this is on a corner and the extra Psi factor here will be small.  Even you are worried about this, then a small airgap (say 5-10mm with spacers between the fasteners to the steel and the blockwork) would drop this 10× to negligible.

 

 

[oranjeboom]

In my extension I had two corner posts (SHS) that will be glazed on either side. I simply applied 10mm aerogel (taped), wrapped with plastic and then drilled timber to all sides. Once windows and doors are attached, I'll use further insulation on the interior where possible.

 

But this is for the heated living room. From the looks of your drawing, you have bi-folds that will close off your 'garden' and will therefore retain some heat and therefore have the potential to cause condensation on the steels - hence the desire to insulate them?

[ToughButterCup]

2 hours ago, TerryE said:

[...]

and these are effectively external structural members.  So why do they need insulated?  Even if these are close coupled to the blockwork, then this is on a corner and the extra Psi factor here will be small.  Even you are worried about this, then a small airgap (say 5-10mm with spacers between the fasteners to the steel and the blockwork) would drop this 10× to negligible.

The reason behind the question was my thoughtless following of our architects notes to the BREGs drawings.

There's no substitute for a sharp mind. You've knocked a few scales off my eyes. (More scales to go, I fear)

 

Cheque's in the post.   

[IanR]

I appreciate this is resolved for RA, but another option for anyone searching for similar in the future:

 

We have 4 Columns of the original cow-shed structure (holding up the roof) that drop into our thermal envelope, and I had to add additional goal-post bracing between each pair as I wanted to move the original racking braces to allow other areas to be opened up:

 

 

We boxed these in with ply and then used a closed-cell spray-on PU foam, (Elastospray 1629/1 from BASF) to insulate, make airtight and stop and moisture getting to them:

 

 

The foam needs to be 60mm thick to guarantee no moisture getting through, but we went thicker anyway to maintain the integrity of the thermal envelope.

[ToughButterCup]

Thanks very much @IanR. It's little gems like the foam needing to be 60mm thick that we need, and indeed which product you used. There are so many out there.

Ian

[eandg]

What did you end up doing @ToughButterCup?