Depth of marmox to minimise bridging

[SBMS]

Am considering using marmox on our door thresholds as others have suggested to minimise thermal bridges. We are doing 180mm PIR that will butt up to marmox thermoblock. Our sliding doors track/bifolds and door cills will sit on the thermoblock. 
 

question is: marmox do a 65mm deep block and a 100mm deep block. How would I go about judging whether the 65mm or 100mm block is preferable/ worth the cost difference?

Edited Friday at 22:10 by SBMS

[Nickfromwales]

6 minutes ago, SBMS said:

Am considering using marmox on our door thresholds as others have suggested to minimise thermal bridges. We are doing 180mm PIR that will butt up to marmox thermoblock. Our sliding doors track/bifolds and door cills will sit on the thermoblock. 
 

question is: marmox do a 65mm deep block and a 100mm deep block. How would I go about judging whether the 65mm or 100mm block is preferable/ worth the cost difference?

The question is, how thick is the screed / constructional slab that sits atop the 180mm PIR? And are the two finished levels matched or are the thresholds slightly raised?

 

That will likely invoke a necessity to install the 100mm, eg so there is an overlap of the Marmox where it meets the PIR (unless my Brewdog Wingman has taken over control of my thoughts).

[SBMS]

11 minutes ago, Nickfromwales said:

The question is, how thick is the screed / constructional slab that sits atop the 180mm PIR? And are the two finished levels matched or are the thresholds slightly raised?

 

That will likely invoke a necessity to install the 100mm, eg so there is an overlap of the Marmox where it meets the PIR (unless my Brewdog Wingman has taken over control of my thoughts).

Ah good point. It’s a 75mm screed but then the track will sit slightly lower as the screed runs nearly level With the top of the track. Are You suggesting that the marmox needs to sit into the PIR and therefore be at least lower than the bottom of the screed?

[Nickfromwales]

11 minutes ago, SBMS said:

Ah good point. It’s a 75mm screed but then the track will sit slightly lower as the screed runs nearly level With the top of the track. Are You suggesting that the marmox needs to sit into the PIR and therefore be at least lower than the bottom of the screed?

If it doesn't, neither of us will wake from our deep sleep tonight, but if possible the two should overlap  

 

Will any of this actually matter(?), remains to ever be documented and evidenced in honesty.

 

For the sake of the polar bears, fit the 100mm is my 2 cents.

 

 

This is what’s in my head. ?  

[SBMS]

12 minutes ago, Nickfromwales said:

If it doesn't, neither of us will wake from our deep sleep tonight, but if possible the two should overlap  

 

Will any of this actually matter(?), remains to ever be documented and evidenced in honesty.

 

For the sake of the polar bears, fit the 100mm is my 2 cents.

 

 

This is what’s in my head. ?  

Thanks Nick. Makes sense I forgot about the screed but in my defence im into a few pints of Spanish lager. 

[Nickfromwales]

36 minutes ago, Nickfromwales said:

Brewdog Wingman

Mothers milk  

[Nickfromwales]

2 minutes ago, SBMS said:

I forgot about the screed

🤣

[JohnMo]

I would read the data sheet (attached) there are rules you need to follow.

 

Thermoblock_Technical_Brochure.pdf

 

But I used thermolite blocks and had no issues, would do so again. Also have a PIR upstand inside the thermolite blocks. So little or no heat escapes.

 

[G and J]

5 minutes ago, JohnMo said:

I would read the data sheet (attached) there are rules you need to follow.

 

Thermoblock_Technical_Brochure.pdf 1.46 MB · 0 downloads

 

But I used thermolite blocks and had no issues, would do so again. Also have a PIR upstand inside the thermolite blocks. So little or no heat escapes.

 

What goes on top of that PIR upstand just inside the door?

[SBMS]

43 minutes ago, JohnMo said:

I would read the data sheet (attached) there are rules you need to follow.

 

Thermoblock_Technical_Brochure.pdf 1.46 MB · 2 downloads

 

But I used thermolite blocks and had no issues, would do so again. Also have a PIR upstand inside the thermolite blocks. So little or no heat escapes.

 

@JohnMo I did consider this. The u value of a thermalite block is about 0.18 and thermoblock is 0.05 so about 3.6x more resistant. But to be honest I have no idea how this translates into real world thermal bridging??

Our current build, the cavity was filled with concrete and you can definitely feel the cold on the floor next to the door threshold. But the thermal resistance of concrete I read was around 0.56 so thermoblock is 10x better and thermalite would be around 3x better. Is it worth it?

[Nickfromwales]

I dislike the porosity of the thermalite block, so it wouldn't be my choice vs Marmox (which has a miniscule value for porosity in comparison).

 

A 'wet' ("atmospherically moist") thermalite block will bridge cold significantly more by comparison. 

[Nickfromwales]

16 minutes ago, SBMS said:

Is it worth it?

If you're going for a quality result, then "why have cotton when you can have silk"? Down to price I guess, so maybe mix & match at the openings for the best overall result (when factoring in a sanity check).

[Tom]

Do you actually need the strength of the marmox? I used compacfoam under our doors, much cheaper and easier to work with

[JohnMo]

7 hours ago, Nickfromwales said:

dislike the porosity of the thermalite block

Both the thermolite and the Marmox are covered up (Marmox from UV, thermolite from atmospheric moisture) - so are they not equal, with different advantages and disadvantages? Install a PIR upstand inside the thermolite block, the bridge has gone anyway.

 

The other factor is what ever sits on the Marmox block has to be wider than the block, the block cannot be an wider than anything sat on it. Thermolite doesn't care so offers a likely more flexibility for construction.

 

8 hours ago, SBMS said:

The u value of a thermalite block is about 0.18 and thermoblock is 0.05 so about 3.6x resistant

Sorry not correct units - those valves are R value, not U value. Then you to take account of the dimensions to get the U Value  

[JohnMo]

Just now, Tom said:

Do you actually need the strength of the marmox? I used compacfoam under our doors, much cheaper and easier to work with

I used this for my roof lights upstairs, very easy to work with, but during our build was readily available in the size I needed for doorways during COVID.

[SBMS]

38 minutes ago, JohnMo said:

Both the thermolite and the Marmox are covered up (Marmox from UV, thermolite from atmospheric moisture) - so are they not equal, with different advantages and disadvantages? Install a PIR upstand inside the thermolite block, the bridge has gone anyway.

 

The other factor is what ever sits on the Marmox block has to be wider than the block, the block cannot be an wider than anything sat on it. Thermolite doesn't care so offers a likely more flexibility for construction.

 

Sorry not correct units - those valves are R value, not U value. Then you to take account of the dimensions to get the U Value  

That’s a good catch yes. Think a lightweight thermalite block is 0.15 thermal

conducrivity so around three times more conductive. @JohnMo do you have a detailing you could share? Did you put the block ‘side on’ so it was 100m deep,

sit your track on it, pir upstand next to the track and then screed up to the block? Ie the same as nick’s brewdog powered drawing but swapping the marmox for insulite? I’ve got quite a few openings so it’s looking like £850 in total For marmox and that’s what I’m trying to weigh up whether it’s worth the additional cost. 

[JohnMo]

49 minutes ago, SBMS said:

do you have a detailing you could share? Did you put the block ‘side on’ so it was 100m deep

See photo up thread of blocks.

 

PIR is on inside of block and floor screed taken up to PIR. Used 70mm PIR upstand around the whole inside perimeter of the floor.

 

[Nickfromwales]

7 hours ago, Tom said:

Do you actually need the strength of the marmox? I used compacfoam under our doors, much cheaper and easier to work with

I’ve used Compacfoam under the doors and sliders, on a previous job (where I had to removed poorly installed units and refit after the installers made a piss-poor job of it all and disappeared). Very good stuff, just need to see here exactly where the cold bridges exists and how deep the product needs to be to created some separation.