Incredibly difficult hole to seal

[j_s]

I think I may have posted about this years ago when we were working on the other side of the hole but I am now working from the internal side. When the house was built back in 2006 by an incompetent builder they decided in their wisdom to bash an almost entire celcon block out instead of core drilling it for the CH and water pipes from the boiler and the cables from the consumer unit that are both in the attached garage. It is extremely difficult access wise, when working from the hallway ceiling that is within the attached garage part of the building we did our best in getting dritherm 32 cavity batts in there which doesn't do a great job I expect if there are pressure changes or wind picks up. Now I am on the last few little jobs in fixing all the issues in the house I want to try and tackle this again.  Part of the plasterboard ceiling will be removed but we will only have up to 110mm wide access to it. The pipes are relatively central to the gap but the cables go off one way for the circuits and then the other and will be very difficult to seal around. I was wondering about a membrane that I could cut to size and tape together in some way that could be glued/taped to the blocks around it (will use a spray primer on the blocks first). On top of this we could box it in to some degree on both sides and above and below, maybe use some 25mm pir board to line the timbers being careful not to encase the cables in the pir board. It's going to be very fiddly no matter what I do but I have tape, timber, airtight paint etc to go at it. I realise that if access is required to this area then it'll be a right pain to get at again but I may just have to live with that for now. My only slight worry is materials used and any possible condensation trapped in some way so I want to make sure that at least is catered for. 

 

No photos yet but we are tackling this in January I expect.

 

In order to remove the pipes and cables and start again would be a monumental task and cost I don't really want to contemplate after all the time and money on the house so far. 

[ProDave]

Have you considered just emptying a can of expanding spay foam in there?

[Mr Punter]

+1 to foam

[markc]

+1 on the foam, might (won’t) look pretty but will work

[Mr Punter]

Given the title I am surprised that @pocster did not gravitate to this thread.

[j_s]

In terms of expanding foam, my main worry were the entirety of the house cabling going through the foam and downrating etc. It is obviously an option if I can get the can in to position, I do have some spare extension sections that may help to get the nozzle in the right place.

Is there a way to work out if it's not a potential overheating risk?

Edited December 13, 2022 by j_s

[markc]

Not an overheating risk through a few inches of foam, burying long runs of cables in insulation prevents heat dissipation but copper being a very good conductor of heat you won’t have any issues as any heat will soon be lost either side of a foam plugged hole

[Carrerahill]

If it was me I would try and close the hole as best I could with bits of brick and mortar around the services, then use fire rated foam to seal the penetrations. 

 

I appreciate it may not be possible to brick it up, but even if I could shrink the hole with some bricks here and there to reduce the size a bit I would. You say the pipes are central and the wires go to the sides, could you fit 2 bricks in on end, one about 50mm from each side to create 3 rectangular openings?

 

It also means you have smaller foam fills and if you can compartmentalise the services into smaller penetrations it would make the whole thing a lot neater. 

Edited December 13, 2022 by Carrerahill

[j_s]

Cheers all. I'll get it opened up and take some reference photos. I'm sure the builder will have some ideas too. I have some spare thermalites we could cut carefully and mortar in (sleeving the pipes of course) if we can get enough access space. 

 

Edited December 13, 2022 by j_s

[Spreadsheetman]

My go-to large hole bodging technique is to use lightweight block and cut to fit with a block saw. Then mortar it in. Add a bit of foam sparingly at the end to seal the remaining gaps.

[j_s]

Here is a what I have to work with which is not much at all unfortunately. 

[Nickfromwales]

Push offcuts of 15mm pushfit pipe or 16mm UFH pipe onto the end of the foam gun, ( taped on extremely well!! ), at around 1000mm long using them as a disposable long-reach nozzle. Inject with Illbruck 330 foam ( airtight, closed cell, excellent stuff ) and job done.

Remove as much of that rockwool as you can, and try to wet the entire cavity immediately before foaming if possible, makes a HUGE difference to how well the foam fills and cures.

 

Do not try to fill all of this in one sitting, so do 1/3, then another 1/3 and then complete as necessary.

 

Aerated blocks aren't airtight btw? Are you parging / painting membrane over them / other?

[Andehh]

Just in case, I was warned by plumber copper pipes degrade in (acidic?) expanding foam... So ensure no exposed copper pipes are there!! 

[Radian]

1 hour ago, Andehh said:

Just in case, I was warned by plumber copper pipes degrade in (acidic?) expanding foam... So ensure no exposed copper pipes are there!! 

That can't be right. Copper HW cylinders are routinely encased in sprayed-on PUR foam. Silicone sealant is slightly acidic, perhaps your plumber was thinking of that?

[j_s]

@Nickfromwales

 

Thanks. 

I'll be using blowerproof paint. 

 

Will remove excess wool insulation first. 

 

Got to sort out this mess too! 

So much for the potential for an airsource heat pump in the future!

3 rad feeds coming off the 22mm to a 15mm which then splits off to a 10mm split to 2 more 10s! Luckily they are close to the boiler and all three get hot even with flow temps set lower. I'll still get a better direct feed to each off the 22. Ideally I'd replace the 22 but I am well passed that with all the other improvements we have already made. I assume 35 main pipe diameter for future proofing? 

 

Edited January 6, 2023 by j_s

[SteamyTea]

4 hours ago, Radian said:

5 hours ago, Andehh said:

Just in case, I was warned by plumber copper pipes degrade in (acidic?) expanding foam... So ensure no exposed copper pipes are there!! 

That can't be right. Copper HW cylinders are routinely encased in sprayed-on PUR foam. Silicone sealant is slightly acidic, perhaps your plumber was thinking of that?

He could have been thinking about copper pipes going though granite, that corrodes pipes pretty fast.

 

If you got a bit of plastic conduit (LSF) and slit it lengthwise, you could fit it over pipes and cables, maybe even wrap it in self amalgamating tape.

Then get happy spirting what you like into the hole.

[j_s]

@SteamyTea

Copper is already wrapped in plastic tubing, I'll use amalgamated tape to seal up the ends of the plastic tubing to the copper. I will also wrap each electrical cable in the same tape so it joins to each other to seal around themselves ( @Jeremy Harris taught me that one for the loft to bedroom cables) unless anyone advises not to do that. I can then wrap the entire cable set too and then foam around those. I might stick some pir board offcuts in the cavity if I can get a hand in there to do so as a bulker/backing for the foam.

 

[Nickfromwales]

3 hours ago, j_s said:

@Nickfromwales

 

Thanks. 

I'll be using blowerproof paint. 

 

Will remove excess wool insulation first. 

 

Got to sort out this mess too! 

So much for the potential for an airsource heat pump in the future!

3 rad feeds coming off the 22mm to a 15mm which then splits off to a 10mm split to 2 more 10s! Luckily they are close to the boiler and all three get hot even with flow temps set lower. I'll still get a better direct feed to each off the 22. Ideally I'd replace the 22 but I am well passed that with all the other improvements we have already made. I assume 35 main pipe diameter for future proofing? 

 

If those 10mm split off which go to 2 more pairs are for heating, then that is total and utter shite. Get it changed. 
All the T’s should each go back to the primary’s. The fact they’re push fit and have inserts to further restrict the flow makes this even worse!!

[PeterW]

3 hours ago, j_s said:

I assume 35 main pipe diameter for future proofing? 

28mm is fine - you’ll need nothing more than that. 22mm is pretty much ok if you push the flow rates up.

 

12 minutes ago, Nickfromwales said:

The fact they’re push fit and have inserts to further restrict the flow makes this even worse!!

And Speedfit….. with no collets… 

[j_s]

Yes I'll be adding all three to the 22s don't worry. I'd like to change the 22 to a 28 but I've already had the ceilings off  and completely redone elsewhere and I may just have to live with 22. If only I had thought about it when I did that a couple of years ago, ****!

[Nickfromwales]

25 minutes ago, PeterW said:

And Speedfit….. with no collets… 

Even worse, as the inserts are 3x thicker than Hep2o….

 

18 minutes ago, j_s said:

Yes I'll be adding all three to the 22s don't worry. I'd like to change the 22 to a 28 but I've already had the ceilings off  and completely redone elsewhere and I may just have to live with 22. If only I had thought about it when I did that a couple of years ago, ****!

Coming off the 22’s will be fine for 10mm feeds, just use a 22x22x15 tee for EACH one ( if copper ) or 22x22x10 tee if you go to Hep2o / same fitting available for JG speed-fit btw, and don’t mix manufacturers!!
 

Link

Edited January 6, 2023 by Nickfromwales

[Pocster]

Sorry ; mis interpreted the title - my bad .

[j_s]

Update. 

 

Yes it's taken me this long to get round to it. 

 

Removed excess Dritherm insulation. 

Cut back plastic pipe very carefully with a dremel. 

Tescon airtight tape around all incoming pipes sealed to plastic protection pipe (stop copper from touching mortar), first used rubber amalgamating tape over cold water feed as the close proximity of me was causing it to get wet from condensation, not much, just enough to stop tape from adhering well. 

I cut 25mm pir board as best as I could around the pipes and cables. Cut it in 2 to make it easier to fit. Using loads of airtight foam to then fix them in place, including the boards to each other.

Let it harden and then foam up all gaps.

Trimmed excess foam. 

Tape pir board joins. 

Used sticks like **** to fill more likely hairline gaps. 

Finally, blowerproof airtight paint over everything.

 

Result, draughts gone. I hesitate to say but I reckon it isn't far off airtight there now. Sitting on the dining room we always had a draught feeling as it's open to the hallway where this hole was before. Now, we don't even with the windy weather recently. True test will be when it gets colder of course. 

 

Edited August 18, 2023 by j_s

[Big Jimbo]

Bloody good effort. Well done.

[Kelvin]

Good effort. Well done.