Filling Chase - previous cause of dampness

[agamemnon]

Hello, 

i previously had issues of dampness caused by the walls and the floors not been properly separated and mortar bridging both. See dampness issue previous post. 
 

I had to resort to make a Chase along the whole area where the mortar was acting as bridge. 
 

I have completed my flooring using - dpm, xps and laminate and now getting to the skirting board. 
 

I want to fill the area with expanding foam, to improve insulation. I have bought the no nonsense expanding foam with a foam gun from screwfix. 
 

My main question is, I can’t find anything about future impact of the expanding foam if it lead to re-emergence of any damp issues. Will the foam cause more moist air to be retained in the Chase? Or will it still evaporate from the floors through the gaps in the foam? 

[Nickfromwales]

22 minutes ago, agamemnon said:

Hello, 

i previously had issues of dampness caused by the walls and the floors not been properly separated and mortar bridging both. See dampness issue previous post. 
 

I had to resort to make a Chase along the whole area where the mortar was acting as bridge. 
 

I have completed my flooring using - dpm, xps and laminate and now getting to the skirting board. 
 

I want to fill the area with expanding foam, to improve insulation. I have bought the no nonsense expanding foam with a foam gun from screwfix. 
 

My main question is, I can’t find anything about future impact of the expanding foam if it lead to re-emergence of any damp issues. Will the foam cause more moist air to be retained in the Chase? Or will it still evaporate from the floors through the gaps in the foam? 

You want to ditch that cheap foam ( open cell ) and use Illbruck 330 ( closed cell ) foam. Goes off much harder, and won't bridge anything, is air and moisture resistant etc.

 

https://www.dortechdirect.co.uk/catalog/product/view/id/5664.html?gclid=Cj0KCQiArsefBhCbARIsAP98hXQJH_IageT-_cHrAyRaxDPZS_RQ6DaqHGqAD-Koxv5kvgILSWaz7hgaAk8SEALw_wcB

 

I don't use anything else these days. Excellent stuff, and ideally suited to your current requirements   

[saveasteading]

I have found that 'no nonsense' and other budget names can be good value but can be inferior. Also a product can change, presumably by commissioning a different supplier.

For anything important i now use a known brand, with a spec sheet.

[agamemnon]

Thanks for clarifying. So if I understand it correctly the foam itself should not retain moisture, but allow it to be permeable so moisture doesn’t build up inside the area? 

[Nickfromwales]

5 minutes ago, agamemnon said:

Thanks for clarifying. So if I understand it correctly the foam itself should not retain moisture, but allow it to be permeable so moisture doesn’t build up inside the area? 

In a nutshell, yes. Nothing will 'build up' in the void filled by the foam, as it will be filled up by the foam! If it's not porous or adversely hygroscopic then it's suitable for preventing damp bridging. It is imperative that you have prepped this meticulously, and have cleaned and primed the surfaces well.  

[Sparrowhawk]

1 hour ago, Nickfromwales said:

You want to ditch that cheap foam ( open cell ) and use Illbruck 330 ( closed cell ) foam. Goes off much harder, and won't bridge anything, is air and moisture resistant etc.

 

https://www.dortechdirect.co.uk/catalog/product/view/id/5664.html?gclid=Cj0KCQiArsefBhCbARIsAP98hXQJH_IageT-_cHrAyRaxDPZS_RQ6DaqHGqAD-Koxv5kvgILSWaz7hgaAk8SEALw_wcB

 

I don't use anything else these days. Excellent stuff, and ideally suited to your current requirements   

 

And the same supplier sells via eBay without the £8 (IIRC) postage charge on a single can of foam. Makes the pennies go further!

[agamemnon]

@Nickfromwales, thank you, that makes sense. The area is completely clean, it appears that I won't be able to start the job today and need to order the items.

 

As I have to order the item's is there any preference of one over the other?

 

Edited February 19, 2023 by agamemnon

[Nickfromwales]

5 minutes ago, Sparrowhawk said:

 

And the same supplier sells via eBay without the £8 (IIRC) postage charge on a single can of foam. Makes the pennies go further!

I buy 12 or 24 at a time with the amount we go through on full installs. Every project is an airtight house so this stuff is brilliant at sealing penetrations etc.

 

5 minutes ago, agamemnon said:

@Nickfromwales, thank you, that makes sense. The area is completely clean, it appears that I won't be able to start the job today and need to order the items.

 

When initially starting off, I read that I would have the option of using expanding foam or expanding foam tape, something like this https://www.dortechdirect.co.uk/tremco-compriband-tp600-2mm-10mm-12-5-metres.html

 

As I have to order the item's is there any preference of one over the other?

 

Foam. KISS. Get a spray bottle and apply a fine mist of water immediately before foaming, working with the process - spray 1m, foam 1m, and keep repeating. The whiff of water makes the foam cure so much better / faster. By the time you finish going around, you'll be able to use a padsaw or similar to cut the first section of foam back flush with the wall.

[agamemnon]

5 minutes ago, Nickfromwales said:

I buy 12 or 24 at a time with the amount we go through on full installs. Every project is an airtight house so this stuff is brilliant at sealing penetrations etc.

 

Foam. KISS. Get a spray bottle and apply a fine mist of water immediately before foaming, working with the process - spray 1m, foam 1m, and keep repeating. The whiff of water makes the foam cure so much better / faster. By the time you finish going around, you'll be able to use a padsaw or similar to cut the first section of foam back flush with the wall.

 

Okay, so essential foam completely fills each nook and cranny, whereas expanding foam tape doesn't. 

[Nickfromwales]

Just now, agamemnon said:

 

Okay, so essential foam completely fills each nook and cranny, whereas expanding foam tape doesn't. 

Tape isn't suitable for anything other than uniform surfaces with complete access, plus there's a much higher chance of them not adhering 100%.

 

Foam, foam, and thrice, foam.

[agamemnon]

 

2 minutes ago, Nickfromwales said:

Tape isn't suitable for anything other than uniform surfaces with complete access, plus there's a much higher chance of them not adhering 100%.

 

Foam, foam, and thrice, foam.

Noted! Thank you.