Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I live in an apartment in a multistoried building. The building is assembled of huge enforced concrete plates - one plate is size of a wall of a room. One of the inter-plate seams has a crack in it due to a slight basement slump (the code allows that) that lets the cold from the outside (the atmosphere) into the apartment.

I need to choose some compound to seal the seam from the inside of the apartment. The crack is about two millimeters wide and I could use ordinary cement-based mortar, but the problem I see is mortar is not elastic, so if the building continues to slump the crack will surely reappear and I'll have to start anew.

I could use silicone-based sealant, but it is not fireproof and I don't like the idea of a fire suddenly bursting from inside a wall if there's a fire in some other apartment.

So I'd like to have something like a cement-based mortar (fireproof) yet flexible enough to compensate fro future slumps. Are there such compounds?

share|improve this question
    
sounds dangerous. –  Asaf Chertkoff Apr 4 '11 at 9:19
1  
@Asaf Chertkoff: Not at all - we have entire cities of such houses and such cracks are considered "requires maintenance" class situations. –  sharptooth Apr 4 '11 at 9:28
    
where do you live? –  warren Apr 4 '11 at 15:29
    
@warren: Very Eastern Europe I'd call it. –  sharptooth Apr 5 '11 at 5:25

3 Answers 3

up vote 5 down vote accepted

I'd opt for a fire resistant silicone sealant such as this one >> http://www.bostik.co.uk/construction/product/bostik/Fireseal-Silicone-Joint-Sealant/340

That's from a UK site, but I'm sure there are similar products in your part of the world.

When it comes to cement then flexibility is usually imparted by including lime in the mortar - although that's a slow process involving the exposed lime within a crack recalcifying over time so not really suitable in your scenario.

share|improve this answer

How about lime puddy? It's elastic and performs like cement You can use Hydrolic lime mix that's very simple - only use with caution! Toxic while wet but the next best thing to nature after dry...

share|improve this answer

i've just read about Polyurea, in hebrew but it says that as a sealing material for concrete:

  1. tensile force of 3500 PSI (suitable for filling concrete cracks) up to 3 mm
  2. can extend to 900% of its original state(!). very flexible.
  3. resistant to heat and even to direct flame (making it fireproof). when the flame Extinguished the Polyurea act as a fire repellent.
  4. and considered in some degree as a "green" material, because of some non-hazardous application characters.

i'm sorry that i don't have a recommendation of a specific product, or even experience with applying it, but it sounds so promising and i needed to share :)

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.