Insulating Steel Columns

[Ay8452]

Hi Folks,

 

I am doing an extension/renovation of my house. I have a few steel beams/columns. I have found a way to bring most/all the steels into the envelope of insulation (warm side) in terms of walls/roof. However I have a few columns that go through the block/beam floor structure and of course the floor insulation (150mm PIR). 

 

Steels going through the floors structure - is that as bad as a cold bridge as them going through the walls/roof? Steels are already in so in order to avoid issues I guess the only thing is to wrap the steels in PIR/tape OR aerogyl but it seems overkill/overspend to do that.

 

FYI Steels are in, Beam Block floor is going to be fitted over the coming weeks, there will be a 500mm void below the beam and block.

 

Thanks!

 

Ali

[JohnMo]

Steel is great conductor of heat. Under block and beam ground will be about 6 degs. Insulation through the floor will make zero difference. The post will be sucking heat from house a very quick rate if not insulated.

 

25mm PIR insulation and plasterboard. 

 

If you have the option to have outside the heated environment, do it. Other insulation is definitely needed

[nod]

The best and easiest way is to use 50 mil MF stud Fix to the floor and ceiling 

Dont make contact with the steel 

[Nickfromwales]

56 minutes ago, Ay8452 said:

I guess the only thing is to

..do what I've just done for a client with rising steel columns which are exposed externally and internally, which is to bond Marmox boards to them.

 

Even if it just 10-15mm it'll kill the cold bridge pretty effectively.

 

https://www.protilertools.co.uk/product/marmox-multiboard-tile---shower-backer-board--choice-of-size-?gad_source=1&gclid=CjwKCAiAtsa9BhAKEiwAUZAszX4ebPdNBF3SV58FmCOrszr1VvIk-Kl56JF44R-c_219F_0ONBT6ExoCmPkQAvD_BwE

 

Fill any gaps with foam NOT mastic  but these can be cut with a track saw etc very accurately.

[saveasteading]

I go with the PIR encasement, simply boxed against it.

Thinking long term. This will be hidden away for ever.

 

Don't be tempted to use mineral wool as it will be lovely for any rodents to live in if they ever find a way in.

PIR will shrink , but it isn't a big issue.

Sticky tape will fail in time. Use wire bands as  ties.

Bitumen paint the steel first, just in case.

[Ay8452]

7 hours ago, saveasteading said:

I go with the PIR encasement, simply boxed against it.

Thinking long term. This will be hidden away for ever.

 

Don't be tempted to use mineral wool as it will be lovely for any rodents to live in if they ever find a way in.

PIR will shrink , but it isn't a big issue.

Sticky tape will fail in time. Use wire bands as  ties.

Bitumen paint the steel first, just in case.

 

Thank you for your response - why the bitumen paint first?

[saveasteading]

1 hour ago, Ay8452 said:

why the bitumen paint first?

Rust. The chances are low, the severity low, but you have one opportunity and it is cheap and easy.

[Super_Paulie]

i had something similar, i think. I used a strip of 10mm aerogel and then boarded over the lot, that section of wall isnt any colder than any other so i guess it worked.

I did notice also that once i had painted the main beam with intumescent paint its no longer cold to the touch, no matter what the temperature outside so i guess that has some thermal properties also.

 

 

[mistake_not]

20 minutes ago, Super_Paulie said:

i had something similar, i think. I used a strip of 10mm aerogel and then boarded over the lot, that section of wall isnt any colder than any other so i guess it worked.

I did notice also that once i had painted the main beam with intumescent paint its no longer cold to the touch, no matter what the temperature outside so i guess that has some thermal properties also.

 

 

Did you do anything for the horizontal steel above? (Got a similar set up going in soon).

[Super_Paulie]

yeah, ground it clean, primed it, intumescent painted it and then eggshell over the top. Probably one of the most long-winded jobs ive ever done in my life as its over 8m long and exposed on 3 sides. Here is a pic of it after the intumescent. 

[saveasteading]

2 minutes ago, Super_Paulie said:

intumescent painted it and then eggshell over the top.

Last time  I checked anyway....

Check the spec for this. Intumescent paint is moisture absorbent, so needs a special, expensive, sealing coat, which can be coloured. Eggshell over that is just decorative, but shouldn't replace the official seal coat...not without checking the properties anyway.

I've never known a bco check intumescent paint spec or thickness*, and so I'm sure a lot of instances receive far less thickness than is specified, and/or no sealing kit.

*(Happy to get an official looking piece of paper from someone. I wonder if that is 'orders' not to get too involved.)

[Super_Paulie]

41 minutes ago, saveasteading said:

Last time  I checked anyway....

Check the spec for this. Intumescent paint is moisture absorbent, so needs a special, expensive, sealing coat, which can be coloured. Eggshell over that is just decorative, but shouldn't replace the official seal coat...not without checking the properties anyway.

I've never known a bco check intumescent paint spec or thickness*, and so I'm sure a lot of instances receive far less thickness than is specified, and/or no sealing kit.

*(Happy to get an official looking piece of paper from someone. I wonder if that is 'orders' not to get too involved.)

 

i used Envirograf in the end, after Rawlins said i couldnt apply the paint myself. Jason at Enviro was extremely helpful all round, did the calculation for me, said i could paint it DIY and when i asked about the topcoat he said, and i quote

 

"If you are going to use your own top coat Paul we advise doing a small test area first to ensure the top coat and intumescent is compatible."

 

I did the test and it was fine so cracked on. For what its worth the topcoat I used ended up the same cost as a tin of paint from Enviro. Once done i got the certificate, gave that to BC with photos of the job and it was signed off. This was about 3 weeks ago and the whole painting process is something im trying to forget, but may never do so...

 

I tested the intumescent on a carboard box with a blowtorch, this stuff actually works.

[Nickfromwales]

So for thinner insulation, Aerogel is significantly better than XPS / Marmox etc?

[Super_Paulie]

14 minutes ago, Nickfromwales said:

So for thinner insulation, Aerogel is significantly better than XPS / Marmox etc?

probably sod all difference, but im always willing to try new tech and it seems to do the job i want it to.

[Nickfromwales]

42 minutes ago, Super_Paulie said:

probably sod all difference, but im always willing to try new tech and it seems to do the job i want it to.

Cost impact for exploration? Or 6 and two 3’s? 

[saveasteading]

1 hour ago, Super_Paulie said:

Enviro was extremely helpful all round,

Envirograf are my favourite too. The original owner was a proper boffin who experimented and created lots of niche objects such as fireproof cat flaps. 

It's great when a small company can survive against the very big companies.

 

How much did the stuff expand when you torched it?

 

A story:

I once handed about 12 pots of intumescent paint to a professional painter and told him how far each tin had to go in length of wall, and why, using as many coats as it took til it was gone.  I think I even laid them around the room to denote each area. Only then could he apply the top coat.

I thought that was easier to understand than using a depth comb.

Did he understand? 'Yes, I know all about fireproof paint'.

Next day, he proudly showed me that he had managed to use only half of the paint, and I could take it back 'it's expensive that stuff'.

Never overestimate the intelligence of your workers. It can be inversely proportionate to confidence.

[Super_Paulie]

33 minutes ago, Nickfromwales said:

Cost impact for exploration? Or 6 and two 3’s? 

10mm PROCTOR Spacetherm® Silica Aerogel STRIPS - 2400mm x 280mm

£35

 

24 minutes ago, saveasteading said:

Envirograf are my favourite too. The original owner was a proper boffin who experimented and created lots of niche objects such as fireproof cat flaps. 

It's great when a small company can survive against the very big companies.

 

A story:

I once handed about 12 pots of intumescent paint to a professional painter and told him how far each tin had to go in length of wall, and why, using as many coats as it took til it was gone.  I think I even laid them around the room to denote each area. Only then could he apply the top coat.

I thought that was easier to understand than using a depth comb.

Did he understand? 'Yes, I know all about fireproof paint'.

Next day, he proudly showed me that he had managed to use only half of the paint, and I could take it back 'it's expensive that stuff'.

Never overestimate the intelligence of your workers. It can be inversely proportionate to confidence.

Yeah i got my calculation of how much it needed and just kept going until the tin was empty, which was almost bang-on 3 coats. Each coat took around 6hrs to put on...

 

24 minutes ago, saveasteading said:

How much did the stuff expand when you torched it?

Video incoming. Not a huge amount but it must have turned into something else when it burnt as it didnt even leave a mark on the inside of a very thin beer can box. No beer was harmed during the making of this video.

 

Setting fire to things

 

 

 

Edited February 17 by Super_Paulie

[saveasteading]

13 minutes ago, Super_Paulie said:

it must have turned into something else when it burnt

That video is great. The carboard seems to be smoking but not burning, which is very impressive. In the tests I have seen the fire made the paint expand about 10 times, and it became a very brittle ash-like material, but that provided insulation. Yours seems to have remained quite robust.

[Super_Paulie]

23 minutes ago, saveasteading said:

That video is great. The carboard seems to be smoking but not burning, which is very impressive. In the tests I have seen the fire made the paint expand about 10 times, and it became a very brittle ash-like material, but that provided insulation. Yours seems to have remained quite robust.

 

No idea how long it would have held up for, obviously I stopped after like 90 seconds as I think my point was proved. Was interesting though and as the beer had been removed from the box I simply had to drink it.

[mistake_not]

5 hours ago, Super_Paulie said:

yeah, ground it clean, primed it, intumescent painted it and then eggshell over the top. Probably one of the most long-winded jobs ive ever done in my life as its over 8m long and exposed on 3 sides. Here is a pic of it after the intumescent. 

Nice!

 

Stupid question: surely there is some cold bridging from the upright steel you insulated with aerogel, to this horizontal steel as they are touching?  Or is it so many minimal it's best ignored?

[Nickfromwales]

5 hours ago, Super_Paulie said:

No beer was harmed during the making of this video.

I've called off the hit  

[Super_Paulie]

3 hours ago, mistake_not said:

Nice!

 

Stupid question: surely there is some cold bridging from the upright steel you insulated with aerogel, to this horizontal steel as they are touching?  Or is it so many minimal it's best ignored?

Who knows, id imagine so but I have no way to measure such a thing. I insulated the upright more to stop condensation behind the plasterboard. All I know is the house is 23° and the beam is warm to touch even though outside is -2°.

Edited February 17 by Super_Paulie