Portal frame insulation

[GrantMcscott]

Hi I have a timber frame house that has a portal frame in it as well.  The house has a 50mm cavity.

 

The Steel I beams should the be insulated in the cavity.  At the minute we have some of the, insulated and some not and all are covered by breathable membrane.

 

i am not 100% sure to insulate them or not due t moisture and just let them have air flow to keep them dry and insulated in the inside of the house or it does not matter.

thanks

 

s

Edited January 1, 2021 by GrantMcscott

[Gus Potter]

Hello Grant.

 

Portal frames are handy things and quite versatile.

 

There are quite a few ways of detailing these up to avoid the thermal bridging.. For all that may be  less familiar with steel portals.. you also want to try and understand where condensation can occur and this can be a little more difficult to deal with when you interface TF with steelwork, particularly if it is a renovation / conversion. For all..one thing is to remember that steel is water proof so any condensate on the inside will not migrate outwards unlike on the TF where you have a breathable membrane on the sheeting ply for example.

 

Once you get a handle on this you can then start to check and develop how you are going to try and fix things to the steel, the tricky bits often occur at the top and bottoms of the steels. You make progress.. then you go back and review the design.. and with renovations this can be quite an iterative process.

 

If you want, post some more photos (panoramic views are helpful as it lets folk see what the steels are holding up and so on) and maybe a few cross sections from your drawings (if you have them) so folk can see how the TF is designed (or not) to interface with the steels.

 

Just as an aside.. what is the white paint? for decor / corrosion control.. or fire?

 

You'll get lot's of good ideas here as you know and one of these may just be the perfect solution for you; save you time and money etc.

 

 

 

 

 

 

 

 

 

 

[GrantMcscott]

2 hours ago, Gus Potter said:

Hello Grant.

 

Portal frames are handy things and quite versatile.

 

There are quite a few ways of detailing these up to avoid the thermal bridging.. For all that may be  less familiar with steel portals.. you also want to try and understand where condensation can occur and this can be a little more difficult to deal with when you interface TF with steelwork, particularly if it is a renovation / conversion. For all..one thing is to remember that steel is water proof so any condensate on the inside will not migrate outwards unlike on the TF where you have a breathable membrane on the sheeting ply for example.

 

Once you get a handle on this you can then start to check and develop how you are going to try and fix things to the steel, the tricky bits often occur at the top and bottoms of the steels. You make progress.. then you go back and review the design.. and with renovations this can be quite an iterative process.

 

If you want, post some more photos (panoramic views are helpful as it lets folk see what the steels are holding up and so on) and maybe a few cross sections from your drawings (if you have them) so folk can see how the TF is designed (or not) to interface with the steels.

 

Just as an aside.. what is the white paint? for decor / corrosion control.. or fire?

 

You'll get lot's of good ideas here as you know and one of these may just be the perfect solution for you; save you time and money etc.

 

 

 

 

 

 

 

 

 

 

Hi, the white paint is meant for corrosion protection.  The builder that put the portal frame up did not paint the steel that went in the ground so raw steel is concreated in.

 

I am worried about water coming in from the outside,and corroding the steel.  As there is block or timber clad and a 50 mm cavity water should not be able to get to the steel I hope.    Some of the steel has breathable membrane over it and some has not and some is painted and some is not and been blocked in.

 

Attached is some of the steel erected and another of what it looked like a few weeks ago.

 

 

 

Edited January 1, 2021 by GrantMcscott

[Gus Potter]

Hello Grant.

 

That looks great, enjoyable to see folk embracing the portal frame principle. Good size house! You have two slightly types of portal as one seems to be creating a large volume, the other supporting a floor.. for the keen the two types of frame perform in different ways depending on the floor level.

 

It kind of looks like a Scottish landscape the trees and grass, maybe Wales I don't know. And that leads me to the steel corrosion. I'll take stab in the dark here but it looks like you may have had some tree stub muncher in so it's hard to see the soil, but looking at the type of trees it may be that you have a shallow clay soil, a bit sandy maybe. If so the soil is likely to be a little acidic such that it promotes a little corrosion compared with a more alkali soil like limestone. I would have a look at the SE spec not just for the steel but also for the grade of concrete used under the ground. If the grade of concrete is high then that may indicate aggresive ground re corrosion potential.. ask your SE. If you are in Scotland then this steel protection should have been speced to get your Building Warrant and the Builder should have followed this specification.

 

It may be that the the detailing is such that the steel is ok re corrosion. Interestingly @Jilly was posting about something similar recently.

 

I would have a word with your SE, if the builder has deviated from the spec then discuss. There are often easy solutions to this.. sometimes you just need to re appraise and all is proved to be ok.

 

The SE may say.. don't worry there is plenty sacraficial steel available to deal with the corrosion so cart on. They may say..mmm I don't know. In this case ask why then raise the possibilty of introducing some cathodic protection. You can find info on this on the web but it't just like protecting a boat from corrosion and it should not be horrifically expensive especially if you good wet clay soil.. There are members of this site that know about all about the physics of this. But simplistically (I think) you could just bury some lumps of zinc  in the ground and electrically bond this to the frame, (check with the Electrician if need be so that what you are doing is compatible with their work) make a note to monitor every five years and get on with enjoying what looks like is going to be a great new home.

 

Hopefully this is some reasurance.

 

 

[GrantMcscott]

37 minutes ago, Gus Potter said:Hello Grant.

 

That looks great, enjoyable to see folk embracing the portal frame principle. Good size house! You have two slightly types of portal as one seems to be creating a large volume, the other supporting a floor.. for the keen the two types of frame perform in different ways depending on the floor level.

 

It kind of looks like a Scottish landscape the trees and grass, maybe Wales I don't know. And that leads me to the steel corrosion. I'll take stab in the dark here but it looks like you may have had some tree stub muncher in so it's hard to see the soil, but looking at the type of trees it may be that you have a shallow clay soil, a bit sandy maybe. If so the soil is likely to be a little acidic such that it promotes a little corrosion compared with a more alkali soil like limestone. I would have a look at the SE spec not just for the steel but also for the grade of concrete used under the ground. If the grade of concrete is high then that may indicate aggresive ground re corrosion potential.. ask your SE. If you are in Scotland then this steel protection should have been speced to get your Building Warrant and the Builder should have followed this specification.

 

It may be that the the detailing is such that the steel is ok re corrosion. Interestingly @Jilly was posting about something similar recently.

 

I would have a word with your SE, if the builder has deviated from the spec then discuss. There are often easy solutions to this.. sometimes you just need to re appraise and all is proved to be ok.

 

The SE may say.. don't worry there is plenty sacraficial steel available to deal with the corrosion so cart on. They may say..mmm I don't know. In this case ask why then raise the possibilty of introducing some cathodic protection. You can find info on this on the web but it't just like protecting a boat from corrosion and it should not be horrifically expensive especially if you good wet clay soil.. There are members of this site that know about all about the physics of this. But simplistically (I think) you could just bury some lumps of zinc  in the ground and electrically bond this to the frame, (check with the Electrician if need be so that what you are doing is compatible with their work) make a note to monitor every five years and get on with enjoying what looks like is going to be a great new home.

 

Hopefully this is some reasurance.

 

 

Hi Gus

The house is in East Ayrshire, the builder has been sacked and went bust.

 

The steel well encased in concrete so no way to get protection to it now, and Architect says it should out last my lifetime.  There was a SE spec but builder ignored it.

 

here is a pick of it going in and in some places there is a metre of concrete below it.

 

Ground is very wet and I will be draining round the house.

 

on the other question should I need to insulate the I section on the outside and do I need water proof paper over it or is the block and cavity enough.

 

 

 

[Gus Potter]

Hi Grant.

 

I'm not too far away from you, based in East Kilbride.

 

Pity it did not work out with the builder.

 

Don't worry too much about the steel that is encased in the concrete.

 

For all, one way to look at this is as follows. For simple domestic stuff it's a bit of a rule of thumb. You'll often see that simple strip foundations have mesh in them. For foundations bearing on the soil the cover to the steel is often specified as being a minimum of 75mm. Roughly the first 25mm is to account for the fact that the machine you dig the found out with can't reasonably get closer than 25mm tolerance (much worse in real life) and pratically ~ 50mm is to account for a bit of the "nesting" of the reinforcement when you lap mesh etc and for soils that are a bit aggresive to concrete) it's all a bit vague. However, roughly the main thing is that is you have a good couple of inches of concrete round your steel and this protects the steel from corrosion for a good while.

 

Grant.. you can see here that once the columns are embedded in the concrete pads that part of them will be ok. It's the little bit just above the top of the concrete that is a little more vulnerable. Practically, your Architect is in my view is on the right side of the argument.. but a key question may be.. will they take that on under their PI cover.

 

The steels in the photos seem to have been reasonably primed , it's just that some of this seems to have been abraded at the bottom when the founds were poured. If push comes to shove then it's a question of examining how much if any of the steel is in direct contact with the soil, the soil type, how much is in the cavity and protected to some extent and how much on the inside is in contact with the inert fill under the floor. This information would be used to underpin an evidence based argument should someone (BC) query the view that the steels as they are good for the design life of the house.

 

In terms of insulating the column. I can't quite see how the kit interfaces with the column but having a guess I would aim to get some good PIR insulation into the web on the outside, then for good measure foam any gaps in case it comes loose later. Here you are already starting to reduce the cold bridging. To make a proper job I think you still have to insulate on the inside but by filling the web on the outside you are going some way to avoiding making a rod for your back later.

 

It would do no harm to keep the continuity of the kit breathable membrane running past the outside of the column as at the very least if you don't do this you'll be creating a weak spot in the vertical lap on the membrane. Much easier to just run it by and staple it to the timber kit each side of the flanges. One thing to look closely at is how the kit is fixed to the steels and plan that bit and the insulation / window details near the steels etc carefully.

 

If you can post some section details so folk can see where the kit sits in relation to the steels you'll get some good positive responses.

 

 

[SuperJohnG]

I've not much to add here but sounds like you're having a pisser after you've had to sack the builder. 

 

Build looks good so far, liking the L shaped skylights I have a few of those on ours too and also I'm in East Ayrshire. 

 

Good luck. 

[GrantMcscott]

9 hours ago, SuperJohnG said:

I've not much to add here but sounds like you're having a pisser after you've had to sack the builder. 

 

Build looks good so far, liking the L shaped skylights I have a few of those on ours too and also I'm in East Ayrshire. 

 

Good luck. 

Yes there is loads wrong floors not level,  he has cut doublers in the roof trusses.  Anything he touched there is an issue with but getting there.

[GrantMcscott]

13 hours ago, Gus Potter said:

The steels in the photos seem to have been reasonably primed , it's just that some of this seems to have been abraded at the bottom when the founds were poured. If push comes to shove then it's a question of examining how much if any of the steel is in direct contact with the soil, the soil type, how much is in the cavity and protected to some extent and how much on the inside is in contact with the inert fill under the floor. This information would be used to underpin an evidence based argument should someone (BC) query the view that the steels as they are good for the design life of the house.

 

Hi Gus,  The build is just outside Muirkirk so not far away.

None of the steel is in contact with soil or the fill under the floor and all the steel is in the timber frame zone hopefully dry zone.

 

Quote

In terms of insulating the column. I can't quite see how the kit interfaces with the column but having a guess I would aim to get some good PIR insulation into the web on the outside, then for good measure foam any gaps in case it comes loose later. Here you are already starting to reduce the cold bridging. To make a proper job I think you still have to insulate on the inside but by filling the web on the outside you are going some way to avoiding making a rod for your back later.

 

So there is PIR insulation in some of the webs and for some off them there is not.  By the time I found this out it had been blocked over.  The top is still open So will try and get some down at least half way.

 

was planning on filling in all the gap with expandable foam.  I will make sure it is well insulated on the inside.

 

 

PROPOSED_SECTIONS.pdf

[hallega]

We are converting a derelict cow shed and are up to the roof. We also have a steel portal system, our Durisol blocks have been cut around the steels for cold bridging, super quilt clad and foamed. Closed cell foamed between roof junction and steel where the 8 m sliding window will be. Photo shows insulation blocks in the beam, these will then be covered in superquilt and then ply.  We also converted 3 metal silos into a house (you tube) if you want to have a look, these being metal were also sprayed with closed cell foam, there was no other way to deal with the metal and condensation forming. The silo's are a year old now, they are wonderfully warm and no problems that we can see as yet. Hope this helps.