Plastic closer by door sill (Ed.)

[seanuk123]

Hi

I’m in the process of laying wood flooring and after taking up the carpet and underlay I found the screed and concrete on the floor inside the front door was crumbling away. I’ve cleared it up and found this plastic item which was filled with concrete.

Can anyone tell me what this is and it it supposed to be where it is?

You’ll see in the photos it’s concrete, then a layer of breeze blocks, then this plastic item (not sure what’s underneath), then the door frame.

The plastic item runs up the walls on both sides of the wall also.

Any advice gratefully received!

 

[freddiemercurystwin]

It's a plastic cavity closer designed to minimise damp, condensation and heat loss from the inner skin (or concrete floor) to the outer skin. https://www.insulationexpress.co.uk/blog/what-are-cavity-closers.html Leave it alone.

 

[seanuk123]

So just to give some extra context there’s a UPVC porch on the other side of the door.

It's a plastic cavity closer designed to minimise damp, condensation and heat loss from the inner skin (or concrete floor) to the outer skin. https://www.insulationexpress.co.uk/blog/what-are-cavity-closers.html Leave it alone.

thank you so much for that! I couldn’t work it out.

Can I re-apply a thin layer of concrete and screed same as the crumbled layer I took off?

Thank you again, I’m really grateful

Sorry for being such a novice!

 

[freddiemercurystwin]

Yes you can screed over it again with something suitable but that will always be vulnerable to cracking, given that the bit over the closer is so thin. Better off asking in the Floors section, I'll ask the mods to move your thread.

 

[seanuk123]

Thanks so much I really do appreciated it.

 

[JohnD]

If repairing small concrete sections, it helps to keep them constantly damp (never allowed to dry out) for a month. You can often do that by wrapping in plastic or clingfilm and misting with a plant sprayer. Do this the day after laying, when it will be stiff enough not to be marked if touched. Dig out all the crumbly stuff so you can lay the best depth of good material.

This is not a joke, concrete really does gain strength by being wet, not by drying out.

Small jobs often dry out too fast, making them shrink, crack, and weak, especially if exposed to heat, draughts or sunshine. That might have happened to the original job.

It will gain 70% of design strength after 7 wet days, and 100% after 28 wet days. If it ever dries out it will stop gaining strength, and will not start again, even if you try to wet it.

 

[seanuk123]

Interesting, I never knew that.

I was thinking of laying some kiln dried sand over the cavity closer to level it out, then I was going to put some screed on the top and smooth it out.

I wasn’t going to use any concrete. Is that right?

 

[JohnD]

If it was me, I'd dig it out, fill it with new concrete mix and trowel smooth.

You'll be walking over it for years to come, and sometimes lugging heavy furniture, cookers and washing machines in and out.

 

[seanuk123]

Thanks John that makes sense.

Would you fill the grooves in the plastic cavity with sand before putting the concrete mix down or put the concrete straight onto the plastic and fill the grooves with it?

I posted another question earlier about some damaged scree in the corner of my dining room. If you have time, is there any chance you could look at the image on that post and see what you make of it?

Thanks again.

 

[seanuk123]

Here is the link to that post:

Help needed - broken screed in corner

Hi I’ve just pulled up the carpet and underlay in the dining room before some new wood flooring goes down next week and found that a piece of screed in the corner of the room is badly cracked / damaged. The piece looks like it’s separated from the rest of the screed and I can push it down...

www.diynot.com

 

[JohnD]

Thanks John that makes sense.

Would you fill the grooves in the plastic cavity with sand before putting the concrete mix down or put the concrete straight onto the plastic and fill the grooves with it?

I posted another question earlier about some damaged scree in the corner of my dining room. If you have time, is there any chance you could look at the image on that post and see what you make of it?

Thanks again.

Clean it out and just concrete for me.

In your case I believe it is in a damp-proof plastic channel. Otherwise I would use DPC or line the trench with DPM to prevent damp from outside getting to the floor of the house. This sort of thing seems to be more common with patio doors than with front doors.