Minimum height of insulation build up on concrete slab

[markc]

I have also seen a lot of corroded columns, once cut a wind brace and the column dropped about 4 inches because the foot had rotted away

[HughF]

This is the sort of mess I have to deal with...

[markc]

4 minutes ago, HughF said:

This is the sort of mess I have to deal with...

Yep, loads of farm building done with pocket founds, then you drop a steel or concrete column into the pocket, erected the building and then fill pocket with concrete. Unfortunately the pocket acts like a tank and holds any water that runs down the columns or pocket sides.

[HughF]

1 minute ago, markc said:

Yep, loads of farm building done with pocket founds, then you drop a steel or concrete column into the pocket, erected the building and then fill pocket with concrete. Unfortunately the pocket acts like a tank and holds any water that runs down the columns or pocket sides.

We use 45 gallon drums for our pole barn bottoms. Dig them into the ground, pole goes in, concrete it up.

[markc]

2 minutes ago, HughF said:

We use 45 gallon drums for our pole barn bottoms. Dig them into the ground, pole goes in, concrete it up.

Yes, done that a few times too, at least this way you don’t form a tank

[HughF]

PP in locally for a class Q conversion on an Atcost concrete portal frame mess of a thing.... It's going to be hard work doing that as half the portal frame has blown.

[seano]

On 23/02/2023 at 11:43, Iceverge said:

@seano

 

 

 

 

 

 

 

 

 

 

That is 2 layers of OSB3 floating 

 

1 layer of this for the UFH (its about £30/m2)

 

110mm of the K103 Phenolic insualtion @ about £55/m2.  157mm.  Total £85/m2 not cheap. 

 

 

You could bin the UFH and use rads and save 25mm and just meet the 0.18W/m2/K limit with just 110mm K103 @ 132mm. 

 

 

 

 

 

 

 

 

 

 

Out of interest, what do you think of these calcs from Superfoil? Do you think this could work? We haven't yet decided on floor finish - could be stone, porcelain tile or wood.

 

February 2023 - Sean O'Halloran - Solid Floor - 2x SFUF and 75mm PIR - 0.13.PDF

[Iceverge]

17 minutes ago, seano said:

 

Out of interest, what do you think of these calcs from Superfoil? Do you think this could work? We haven't yet decided on floor finish - could be stone, porcelain tile or wood.

 

February 2023 - Sean O'Halloran - Solid Floor - 2x SFUF and 75mm PIR - 0.13.PDF 487.87 kB · 0 downloads

 

 

Not much I'm afraid. 

Even by their own (very optimistic) calculations you'd be better off replacing the 6mm+6mm of Superfoil with 12mm of PIR. Then you'd end up at about a U value of 0.025W/m2K without any shenanigans regarding ground conductivity and perimeter areas.   

 

There's no BBA cert for their floor products. From the BBA cert for their wall products if you squash it between studs and battens it has zero thermal resistance. 

 

It relies on stationary air (like most insulants) to give any thermal resistance. The low emissivity (shiny) foil may help in cold loft situations to keep temperatures lower under direct sunlight but it does almost nothing to keep the heat in. 

 

 

 

In short there's better places to put your money. 

[seano]

On 23/02/2023 at 11:43, Iceverge said:

@seano

 

 

 

 

 

 

 

 

 

 

That is 2 layers of OSB3 floating 

 

1 layer of this for the UFH (its about £30/m2)

 

110mm of the K103 Phenolic insualtion @ about £55/m2.  157mm.  Total £85/m2 not cheap. 

 

 

You could bin the UFH and use rads and save 25mm and just meet the 0.18W/m2/K limit with just 110mm K103 @ 132mm. 

 

 

 

 

 

 

 

 

 

 

 

Me again. If we kept the UFH, would the floor finish (floorboards or porcelain tile, go ove the top of the build up you have illustrated or replace the top layer?

 

[Iceverge]

No my area of expertise I'm afraid. 

 

Porcelain would certain need something solid. I imagine it would be much the same as tiling over floorboards. 

 

 

[hellopaul]

Thought I'd join in with this thread (or maybe I should start a new one):

I'm doing a barn conversion, and I'd like to pick the brains of anyone's knowledge of insulation to ask what is the most effective insulation to use with UFH? I currently have a concrete slab (over blinding/DPM) which will then have (probably) 100mm Celotex (100mm = R-value of 4.5...according to Celotex), then a layer of whatever the screed company want, underfloor heating pipes, liquid screed then engineered hardwood flooring. I'm keen to keep the floor as low/thin as possible, to maximise ceiling heights, so wondered if there's anything out there that would do a better job of insulation than the Celotex, so I could either keep the insulation thickness at 100mm but get a better R-value, or have, say, 75mm of a better product that'd have the same R-value as 100mm of Celotex? The floor is about 100sq.m in total.

 

Any thought and suggestions would be very welcome, thanks!

Edited April 21 by hellopaul

[saveasteading]

On 21/04/2024 at 17:58, hellopaul said:

barn conversion

What is your floor at present?

[Chanmenie]

On 21/04/2024 at 17:58, hellopaul said:

Thought I'd join in with this thread (or maybe I should start a new one):

I'm doing a barn conversion, and I'd like to pick the brains of anyone's knowledge of insulation to ask what is the most effective insulation to use with UFH? I currently have a concrete slab (over blinding/DPM) which will then have (probably) 100mm Celotex (100mm = R-value of 4.5...according to Celotex), then a layer of whatever the screed company want, underfloor heating pipes, liquid screed then engineered hardwood flooring. I'm keen to keep the floor as low/thin as possible, to maximise ceiling heights, so wondered if there's anything out there that would do a better job of insulation than the Celotex, so I could either keep the insulation thickness at 100mm but get a better R-value, or have, say, 75mm of a better product that'd have the same R-value as 100mm of Celotex? The floor is about 100sq.m in total.

 

Any thought and suggestions would be very welcome, thanks!

Is the concrete slab already poured ?

[Iceverge]

To feel any heat through the engineered wood flooring you're going to need very high flow temps. This will kill the efficiency of any heating system, espically an ASHP and will exacerbate any downwards heat losses.

 

As its an old conversion it'll lightly have higher heat losses and an intermittent heating strategy is probably the most economical. In this case you need to concentrate on heating the internal air rather than the structure. Get rid of the UFH and use large radiators. 

 

From your other post you have 100mm plus 70mm screed and engineered flooring planned. Let's say 20mm for that. Total 190mm.

 

Phenolic insulation is slightly better than PIR but almost never worth it in a financial sense. 

 

This is my recommended build up:

 

20mm engineered flooring glued down. 

18mm T&G OSB layed at 45deg to the engineered flooring, glued together. 

50mm PIR

100mm PIR with joints staggered to upper layer. 

Levelling compound over concrete slab. 

 

U value about 0.14W/m2K.

 

The engineered wood will be warm underfoot in any case but I would consider adding electric UFH matt on any tiled areas just for the extra comfort. 

 

 

 

 

 

 

 

 

[hellopaul]

The floor is currently a concrete slab, poured last year. It is a new barn conversion - it's not finished yet.

 

From what I can find, people do generally seem to like underfloor heating with engineered wood: https://www.mumsnet.com/talk/property/4839419-engineered-wood-floor-with-underfloor-heating

(not the pinnacle of construction technology forums I know, but real people with real experiences).

 

It might be easier to look at another post I added to where I go into more detail: