Steel column thermal bridge - why do I feel like I’m doing the design team’s work for them?!?

[Great_scot_selfbuild]

We have steel columns (250mm square cross-section) in the corners of our timber frame with steel lintels which allows for glass on 3 sides. The steel is visible inside & out, and although I’ve been asking for the detail for some months, only now that we’re very close to installation have I established that none of the design team (Principal Designer - architectural designer), Timber frame manufacturer (designer, structural engineer, production manager…) has mentioned it until I have pointed out that there’s no insulation in it (on the drawing).

 

The drawing 

 

I'm concerned that there's been no design discussion about how they will be prevented from becoming a very significant thermal bridge.

 

Cue silence…

 

In the interest of now finding a solution rather than playing a blame game (adds no value), I’m seeking this group’s thoughts and experience.

 

One suggestion has been to drill holes to inject expanding insulation into the column, with holes positioned in line with where the window frames will go (this method would need more than one hole to get it in far enough and fill the full height; the holes could be subsequently weld-filled afterwards, and this would obviously need approving by the structural engineer).

 

 

AAAAARRRRRRRGGGGGHHH!!!! So frustrating….

[Mike]

Not the first time we've had that stupidity. Since it's presumably too late to reposition the post here's one potential solution - search for others.

 

 

11 minutes ago, Great_scot_selfbuild said:

One suggestion has been to drill holes to inject expanding insulation into the column

The cold will still travel through the steel, bypassing the insulation so not going to solve the problem.

 

[Great_scot_selfbuild]

36 minutes ago, Mike said:

Not the first time we've had that stupidity. Since it's presumably too late to reposition the post here's one potential solution - search for others.

 

 

The cold will still travel through the steel, bypassing the insulation so not going to solve the problem.

 

 

The original design was for the column to be inside the windows, but the timber frame structural engineer stated that it ‘had’ to go in the corner. TBH this really hacked me off that they weren’t able to calculate a small cantilever for the loading. Ultimately I trusted the collection of design professionals involved in the whole build / design (and I had them all join joint design meetings). I’ve got to the point where it can’t be changed now, and in the general scheme, we can come up with a solution I expect using the Aerogel type of product.

 

Yes, it’ll still have the steel passing through, but the internal being empty wouldn’t help.

 

Thanks for the link to an earlier thread - I’ve only read part of it so far, but it’s already giving me confidence in finding a solution. TVM!

[Annker]

57 minutes ago, Great_scot_selfbuild said:

We have steel columns (250mm square cross-section) in the corners of our timber frame with steel lintels which allows for glass on 3 sides. The steel is visible inside & out, and although I’ve been asking for the detail for some months, only now that we’re very close to installation have I established that none of the design team (Principal Designer - architectural designer), Timber frame manufacturer (designer, structural engineer, production manager…) has mentioned it until I have pointed out that there’s no insulation in it (on the drawing).

 

The drawing 

 

I'm concerned that there's been no design discussion about how they will be prevented from becoming a very significant thermal bridge.

 

Cue silence…

 

In the interest of now finding a solution rather than playing a blame game (adds no value), I’m seeking this group’s thoughts and experience.

 

One suggestion has been to drill holes to inject expanding insulation into the column, with holes positioned in line with where the window frames will go (this method would need more than one hole to get it in far enough and fill the full height; the holes could be subsequently weld-filled afterwards, and this would obviously need approving by the structural engineer).

 

 

AAAAARRRRRRRGGGGGHHH!!!! So frustrating….

Have the windows been ordered, measured to the SHS?

If they have that would then limit the choice of solutions; but if not there appears to be little preventing a conventional solution being found if your design team put their heads together. 

[Nickfromwales]

28 minutes ago, Great_scot_selfbuild said:

 

The original design was for the column to be inside the windows, but the timber frame structural engineer stated that it ‘had’ to go in the corner. TBH this really hacked me off that they weren’t able to calculate a small cantilever for the loading. Ultimately I trusted the collection of design professionals involved in the whole build / design (and I had them all join joint design meetings). I’ve got to the point where it can’t be changed now, and in the general scheme, we can come up with a solution I expect using the Aerogel type of product.

 

Yes, it’ll still have the steel passing through, but the internal being empty wouldn’t help.

 

Thanks for the link to an earlier thread - I’ve only read part of it so far, but it’s already giving me confidence in finding a solution. TVM!

On a few previous clients projects, similar circumstances, I clad the steels with 20mm Compacfoam, and the client ordered the fenestration with the deductions in width made accordingly.

 

Then I employed a designer / installer for alu cappings to be made, and RAL sprayed to colour match, and results were perfectly satisfactory. 
 

I actually preferred that to the option of dragging the steel inboard, so maybe a review would change your mind; at least put it at ease a bit anyways. 

[Great_scot_selfbuild]

22 minutes ago, Annker said:

Have the windows been ordered, measured to the SHS?

If they have that would then limit the choice of solutions; but if not there appears to be little preventing a conventional solution being found if your design team put their heads together. 

Yes, ordered. Frustratingly, there were many design discussions where this should have been raised by those who do it for a day job (and were being paid to…). I’m more than a little angry😡

[Annker]

17 minutes ago, Great_scot_selfbuild said:

Yes, ordered. Frustratingly, there were many design discussions where this should have been raised by those who do it for a day job (and were being paid to…). I’m more than a little angry😡

I currently have near a identical arrangement to your sketch with added issue of the sliding doors installed.

 

In my case it's my own fault as I was involved with the design.

I thought my sliding door supplier/installers were on the ball, and otherwise I am very happy with them, but I am wondering how they didn't flag my oversight of insulation when these detail are bread and butter to them.

 

Two options I'm considered are either:

Insulate the SHS externally and suffer that insulated SHS pressing will step past the face of the frame.

or insulate internally and do not insulation externally, this will allow the external SHS cover pressing finish flush with the face of the frame but greater risk of a cold bridge.

 

My frames are alu and not thermally broken so perhaps it's more of an annoyance that a material issue. 

 

[Nickfromwales]

7 minutes ago, Annker said:

Two options I'm considered are either:

Insulate the SHS externally and suffer that insulated SHS pressing will step past the face of the frame.

or insulate internally and do not insulation externally, this will allow the external SHS cover pressing finish flush with the face of the frame but greater risk of a cold bridge.

 

My frames are alu and not thermally broken so perhaps it's more of an annoyance that a material issue. 

Exactly what I faced on one job, and opted to not insulate externally; the design I gave the client for that featured a very generous bead of mastic to affix the aluminium to the steels, with continuous beads at foot and head to stop convection through any otherwise resultant free air space.

 

To date, no complaints, and a far lower profile solution from the exterior aspect 👍. 
 

Compromises can be made successfully if managed meticulously, that’s the ‘gotcha’. 

[Annker]

21 minutes ago, Nickfromwales said:

Exactly what I faced on one job, and opted to not insulate externally; the design I gave the client for that featured a very generous bead of mastic to affix the aluminium to the steels, with continuous beads at foot and head to stop convection through any otherwise resultant free air space.

 

To date, no complaints, and a far lower profile solution from the exterior aspect 👍. 
 

Compromises can be made successfully if managed meticulously, that’s the ‘gotcha’. 

Yes Nick that is the finish I had in my head and the one I mentioned to my sliding door firm at design stage. 

IIRC they agreed that was the usual way its done, but the now wiser me can clearly see that it is far from the best way to do it.

 

   

 

 

[bmj1]

It's amazing how much you learn the first time.

 

I'm working on my second self build right now (it's a community project), following my own self build. I plan to check every single detail myself.

 

Nobody else actually cares. Not to the same level.

[Nickfromwales]

52 minutes ago, Annker said:

Yes Nick that is the finish I had in my head and the one I mentioned to my sliding door firm at design stage. 

IIRC they agreed that was the usual way its done, but the now wiser me can clearly see that it is far from the best way to do it.

 

   

 

 

Life is full of compromises, just best to be in direct control of them when they arise. 
 

Otherwise they become ‘cosmetically acceptable’ failures…..

[Mattg4321]

Should the steels be galvanised if outside the thermal envelope?? 
 

My SE insisted on it with a couple, but not sure if entirely necessary, but seemed like a sensible idea. 

[Great_scot_selfbuild]

9 hours ago, Nickfromwales said:

Exactly what I faced on one job, and opted to not insulate externally; the design I gave the client for that featured a very generous bead of mastic to affix the aluminium to the steels, with continuous beads at foot and head to stop convection through any otherwise resultant free air space.

 

To date, no complaints, and a far lower profile solution from the exterior aspect 👍. 
 

Compromises can be made successfully if managed meticulously, that’s the ‘gotcha’. 

This is (slightly) encouraging. Do you have any photos of this by chance? Was the internal face of the steel covered or were both sides left visible/uncovered?

[Great_scot_selfbuild]

1 minute ago, Mattg4321 said:

Should the steels be galvanised if outside the thermal envelope?? 
 

My SE insisted on it with a couple, but not sure if entirely necessary, but seemed like a sensible idea. 

They don’t have to be. We have a steel ring beam and columns - they have 2 coats of zinc oxide and 2 coats of bitumen. Galvanizing would have added a lot of time & many thousands £££

[saveasteading]

It's for your Principal Designer to resolve. Their only excuse is if design detail and  changes have not been presented to them.

 

I think you must fit as thick  layer of foam board on the outside, as works. May only be 10mm but do it. As @Nickfromwales.

Then also insulate thre inside face later.

Filling the box section is pointless. 

 

That will fall far short of any target U values but is much better than nothing, and the area is small.

To help tick a box, use the U values for windows as your comparison.

Then add more indulation somewhere else.

But ask  the PD.

 

[Nickfromwales]

2 hours ago, Great_scot_selfbuild said:

This is (slightly) encouraging. Do you have any photos of this by chance? Was the internal face of the steel covered or were both sides left visible/uncovered?

2 sides clad in insulation and windows up against those, small alu capping internally to match window frames, then just alu cappings again externally. 
 

I had the external one made up in 2 pieces, to ease fitment (and manufacturing). 
 

No pics sorry, I had departed soon after sorting designs as these took some time to manufacture, powder coat, and for the installers to then book the clients in.

 

Once I’ve broken the back of a job for people I’m usually then off to the next one, only then staying in contact for remote assistance, such as this type of ‘last minute’ detailing and problem solving; a lot of this goes on as the design and pre-construction phases are often just skipped though sadly. 

[Annker]

2 hours ago, Great_scot_selfbuild said:

They don’t have to be. We have a steel ring beam and columns - they have 2 coats of zinc oxide and 2 coats of bitumen. Galvanizing would have added a lot of time & many thousands £££

Definitely recommend any exposed steel to be galvanised and the additional cost on a domestic job should only be in the early to mid hundreds.

You look sideways at zinc oxide and it scratches.  

[saveasteading]

Galvanising is not essential steel only corrodes if wet. Yours should never be.

Paint it with an expensive product made for the purpose.

 As it will be concealed it doesn't have to look good.

Beneath the base plate is the highest risk. Make sure all detailing keeps this dry. If it is on grout then bitumen paint it.