Should i insulate an internal steel?

[Friendlyengineer]

SO : We have just had installed an internal steel frame where we've taken a wall out inside our house (1850s , back to brick, im aiming for Enerphit having done no calcs 🙈) . The bottom part of it is in the ground enclosed in concrete, and the side posts are bolted to the internal walls.

I've attached a bit of our structural engineers drawings below for reference.

Our builder has already boxed all of this in , but i cant help feel I should have wrapped the bits of steel I can see in something like an aerogel sheet https://phstore.co.uk/spacetherm-aerogel/ .

I've done exactly 0 calculations and am just aiming high for insulation and airtightness.

Is that enough info for people to have some thoughts about?

Thanks all, I appreciate your time

 

Mark

 

 

[saveasteading]

I don't understand the context. Why is a steel beam in the ground? What is above the top beam?

Is it a heated and insulated space? 

How can you be going for passiv certification without having designed for it?

[ETC]

It’s internal in a heated space. Why do you want to insulate it?

[SteamyTea]

If any part of it goes into, or touches a colder region, then you may want to insulate it.

Aerogel derived products are a very expensive way to replace some PIR.

[Gus Potter]

4 hours ago, ETC said:

It’s internal in a heated space. Why do you want to insulate it?

It's this thing where folk think PH and you need to eliminate every cold bridge.. even columns that are internal.. it looks great on paper but the cost outweighs the benefit.. your door handles are a cold bridge for example.

 

Building houses requires a common sense and practical approach.

1 hour ago, SteamyTea said:

If any part of it goes into, or touches a colder region, then you may want to insulate it.

Aerogel derived products are a very expensive way to replace some PIR.

Yes you do to you achieve a back stop U value. For a column like this that is founded say 450mm below finished floor level then it may achieve the back stop U value anyway with the fire protection and associated air gap.

 

5 hours ago, Friendlyengineer said:

Is that enough info for people to have some thoughts about?

Yes it usually is enough.

[Friendlyengineer]

 

 

16 hours ago, saveasteading said:

I don't understand the context. Why is a steel beam in the ground? What is above the top beam?

Is it a heated and insulated space? 

How can you be going for passiv certification without having designed for it?

 

The steel is a whole frame designed by our Structural Engineer. I assume because the internal wall next to it is quite thin, and I didnt want a big pillar sticking out into the room , so thats just how he designed it.

Yes, its heated and will be insulated.

Yea ... Ha, the passiv certification thing. We are definitely not going to be certifying anything, I'm just putting products in our house that will push us beyond the current building regs towards Enerphit standards. I've got no intention of certifying it because there are places where it will fail miserably , like the current double glazed windows for example. They are not that old, so we dont have the money to replace them in this project.

[Friendlyengineer]

11 hours ago, Gus Potter said:

It's this thing where folk think PH and you need to eliminate every cold bridge.. even columns that are internal.. it looks great on paper but the cost outweighs the benefit.. your door handles are a cold bridge for example.

 

Building houses requires a common sense and practical approach.

Yes you do to you achieve a back stop U value. For a column like this that is founded say 450mm below finished floor level then it may achieve the back stop U value anyway with the fire protection and associated air gap.

 

Yes it usually is enough.

My wife is my commonsense , and I absolutely know the cost outweighs the benefits, but she tells me Im a perfectionist so I try and look for every tiny thing i can improve very often without looking at the cost...... My builder agrees with her and you all by the way!

 

Very good point about the door handles.! Im certainly not oblivious to the requirements we want to achieve, the actual reality of that , and the fact we havent had a designer do proper calcs for us, I think which is why im just a bit stressed about pushing everything to it's extreme where its just not needed.

 

 

[Friendlyengineer]

Thanks all, this has been a simple , but good sanity check. I appreciate it.

 

 

[Kelvin]

It’s the curse of the self-builder. You want to micro-manage every detail because you understand just enough to make you think about it but don’t have the technical knowledge and experience to know when to back off. For example, on the steel beams into concrete footings. Mine are too and I planned to fit thermally isolating blocks under the steels to separate them from the ground. However there were too many things happening all at once at the time that I didn’t get around to ordering them ahead of the steels going in. I fretted about this for ages! 

[IanR]

18 hours ago, Friendlyengineer said:

I've done exactly 0 calculations and am just aiming high for insulation and airtightness.

 

On the assumption that you have a ground bearing slab that is integrating that horizontal UB "concrete encased", I would look into whether it's possible to get some thermal analysis completed.

 

Unless the whole house was to PH levels then the cold bridging itself isn't going to move the heat loss needle too much, but do you need to mitigate a condensation risk?

 

 

If the slab is ground bearing, the concrete and that horizontal UB will be at 8°C - 10°C. My question is what temp will UC be at as it pokes out of your FFL and is in contact with the internal moist air? If it's under 13°C or 14°C you have a condensation risk. As it's boxed in you won't see any tell tale water pooling.

 

I don't know if the typical architectural software packages can do this type of thermal modelling, I used an automotive CFD thermal analysis package to work out the steel columns in my conversion would give me a condensation issue.

[Kelvin]

Columns into concrete with no thermal break seems to be common practice. I’ve seen many builds like this. However, I did insulate all the steel beams including the two that are inside the thermal envelope of the building. 

[Friendlyengineer]

1 hour ago, Kelvin said:

It’s the curse of the self-builder. You want to micro-manage every detail because you understand just enough to make you think about it but don’t have the technical knowledge and experience to know when to back off. For example, on the steel beams into concrete footings. Mine are too and I planned to fit thermally isolating blocks under the steels to separate them from the ground. However there were too many things happening all at once at the time that I didn’t get around to ordering them ahead of the steels going in. I fretted about this for ages! 

Thats exactly me... in fact, I was looking into exactly the same thing to put a thermal break into the steels , but like you i didnt get down to it in my list in time ....... and yes, ive also fretted about this for ages.

 

[Gus Potter]

Quick reality check folks.

 

Make things complex on site and you'll often pay for something that never gets delivered by the contractor. Wrapping the bottom of internal columns in Aroegell is daft.. because you need a small quantity (costs a lot) and someone has to go in the van to go and get it! That excercise just to procure the stuff could cost you £150 -300 or more which could pay for a lot of thicker insulation elsewhere at no risk.

 

You may need fire protection so a bit of extra glass wool solves the problem and get you below the 0.7 U back stop value to stop regular condensation.

 

The key thing that a lot of folk seem to be missing here on BH is that you can do a compensatory U value calculation.

 

If you have a steel column poking out inside the house you need to make sure it does not drip with condensation. Again a back stop U value of 0.7 is about right with a vapour barrier to be on the safe side. There is a massive diference between an internal column and a steel column on the external wall in terms of cold bridging. An internal column is founded on the heated dumpling of soil so the heat loss is much less that the basic software is often telling you.

 

You then compensate for the extra heat loss by beafing up other parts of the insulation envelope. But for such a small extra heat loss from an internal column.. it's next to nothing.

 

This is a common sense approach that a lot of folk on BH are missing.