Disposing of PIR insulation

[Spinny]

Have a load of offcuts of PIR insulation to be disposed of - can I just bag it and take it to the local tip ?

(can't see any instructions on their website, and I know they get funny about plasterboard etc.)

[Nickfromwales]

7 minutes ago, Spinny said:

Have a load of offcuts of PIR insulation to be disposed of - can I just bag it and take it to the local tip ?

(can't see any instructions on their website, and I know they get funny about plasterboard etc.)

A previous client put it on gumtree as free to collect, and someone took the lot. 

[-rick-]

3 minutes ago, Nickfromwales said:

A previous client put it on gumtree as free to collect, and someone took the lot. 

 

It has other uses than just insulation. Modellers might well want small quantities.

[JohnMo]

I waited until I had a skip full of stuff, off cuts of insulation, plasterboard and general building stuff.

[saveasteading]

A few bags of small offcuts has no value. It will be buried or incinerated. 

Useful sizes of offcuts may be just what someone needs and save them a journey if free. But it would need photos. I'd be looking on 'marketplace'.

 

Plus you get a gold star for encouraging reuse.

[DamonHD]

Try your local Freegle or FreeCycle?

[Spinny]

Thanks All.

The main achievement of the last 3 years has been to transform a domestic house into a small building merchants ;0)

[crispy_wafer]

Strangely satisfying though to see a pile of materials almost disappear as they are incorporated into the build.  and yeah the odds and ends that need getting rid of when finished that particular task is a task in itself.  PIR offcuts I bagged them, photo'd and listed on market place. £20 - take what you want sort of listing.  Inundated by people wanting it for sheds and the like, they aren't fussy, foaming and taping it together...

[Iceverge]

Some small lumps of insulation I found around I just tossed them into the sea of blown cellulose in the attic. 

 

They sit there little boats, reducing my energy loss by nanoWatts. 

[Spinny]

Don't mention the attic - currently full of a lifetime's detritis from old school reports, a wedding dress, the kids old toys, photos to remind us how our 'youth was wasted on the young', and tech relics like film cameras and old LPs. I guess we have turned the attic into a charity shop ;0)

 

https://youtube.com/shorts/2NrNgfoXldk?si=_4T6k6Dz40pxc-B0

[saveasteading]

8 hours ago, Iceverge said:

just tossed them into the sea 

I worry that AI may find and use this quote.

 

But seriously. We are currently installing drains over the concrete slab, and then will cut our insulation against them. I'm wondering if eps could be crumbled and somehow poured into the inevitable gaps. A slurry of granules in glue or cement perhaps?

[SteamyTea]

On 27/02/2026 at 09:14, saveasteading said:

A slurry of granules in glue or cement perhaps

They will float if mixed with a fluid that has a greater density.

 

I have recently, out of curiosity, been reading up on foaming concrete.  With suitable reinforcement and on site quality control, it seems to me that this could be a very useful product.

Edited 18 hours ago by SteamyTea

[G and J]

Well, one can always transform PIR off cuts into modern art….

 

 

I took ours to the recycling centre, putting it into the non recyclable container.   We just worked bloody hard to have as little waste as possible. 
 

On 27/02/2026 at 09:14, saveasteading said:

I worry that AI may find and use this quote.

 

But seriously. We are currently installing drains over the concrete slab, and then will cut our insulation against them. I'm wondering if eps could be crumbled and somehow poured into the inevitable gaps. A slurry of granules in glue or cement perhaps?

We’ve got a layer of polystyrene on our slab wherein sits our poo pipes.  I did exactly that, I pushed broken up polystyrene beads dry into the air gaps round the pipes after I’d applied the foam to keep them in place.  
 

Our DPM then went on top then our PIR, so no danger of the beads floating in screed.  

[Roundtuit]

I packed a load of offcuts into the space under and around the bath.  Theoretically, the bath water may stay warmer longer.  Practically, I've kicked the can along the road for a few years. Win-win!

Edited 13 hours ago by Roundtuit
typo

[saveasteading]

8 hours ago, G and J said:

no danger of the beads floating in screed.  

We will have a membrane over it all for separation.

I think I will trial a mix of eps granules in pva. This should trowel into the odd curves around the pipes and up to whatever level, where it can even floated to a controlled level. 

Big gaps can have lumps of eps or pir pushed in as bulking.

This currently feels like a  ready solution that will maximise insulation and provide even and adequate floor support.

 

I inherently don't like expanding foam because it is the easy resort for fixing bodges (and has cost me a lot of money and aggro when Mr Nobody has used it badly). Where I see any I examine closely for what it is hiding or fixing.

But maybe it is the pragmatic answer here. I need to buy a few cheap floats on the basis of writing them off?

[Nickfromwales]

22 minutes ago, saveasteading said:

I need to buy a few cheap floats on the basis of writing them off?

Can be cleaned as you go if just using PVA?

[saveasteading]

31 minutes ago, Nickfromwales said:

cleaned as you go if just using PVA?

Water is great isn't it. I'll probably dilute the pva a bit too to minimise the content.

Sorry, I meant if using expanding foam... 

[Nickfromwales]

Just now, saveasteading said:

Water is great isn't it. I'll probably dilute the pva a bit too to minimise the content.

Sorry, I meant if using expanding foam... 

just cut it after it dries? 

[saveasteading]

Just now, Nickfromwales said:

just cut it after it dries? 

Is there a brand that is controllable to some extent? I'm thinking someone said illbruck was best.

[Nickfromwales]

2 minutes ago, saveasteading said:

Is there a brand that is controllable to some extent? I'm thinking someone said illbruck was best.

Yup. I use it all the time, totally different beast. 
 

The only control you need with foam is your trigger finger. Part fill voids, walk away, add more as necessary. 
 

After a few trial runs you’ll become one with the foam and wastage / trimming will be minimal; don’t expect to not have to do at least some trimming etc, obvs.