gaps in my cavity insulation. a big deal or no?

Linto

Hi guys,
The builder started building the extension today (cavity wall). I had a look this evening and notice a slight gap in the insulation (see picture attached). Is this something I should insist on having corrected or is a small gap like that normal enough?

(I don't want to create any unnecessary agro)
Thanks!

GreeBo

theres some nice thermal bridging going on there with the messy mortar anyway.

Insulation should be solid without any gaps otherwise its effectiveness drops off a cliff. Think of a water proof jacket that has some gaps in the stitching...you are going to get wet, irrespective of how good the fabric is.

muffler

Hand him a lump hammer in the morning and tell him to sort it. Pure shite is the only way I would describe that

risteard7

An odd small gap here and there will happen, but that gap seems a bit big. it's lazy by the builder. If most of the boards have gaps that size between them i would say it.

Sometimes if you're struggling to close a gap you might join two boards with a nail to hold them in place

Linto

muffler wrote: »

Hand him a lump hammer in the morning and tell him to sort it. Pure shite is the only way I would describe that

All the rest of the wall seems fine. This was the only area I noticed a gap. Would you still insist on repair? Does that mean taking that part of wall down?

muffler

Linto wrote: »

Would you still insist on repair? Does that mean taking that part of wall down?

I certainly would insist on the boards being butted correctly. It will only involve the removal of a few blocks but its not only the insulation, its also the mortar snots as they are referred to in the trade.

If you haven't got a professional carrying out inspections of the works I would recommend you get one.

GreeBo

it looks like that last piece was just cut too small.
The fact that there appears to be a couple of cms either side, in my mind at least, effectively means that the last piece is not there at all, its not stopping any air movement in any direction, you might as well have a 3 inch gap as that piece.

Linto

GreeBo wrote: »

it looks like that last piece was just cut too small.
The fact that there appears to be a couple of cms either side, in my mind at least, effectively means that the last piece is not there at all, its not stopping any air movement in any direction, you might as well have a 3 inch gap as that piece.

So would you insist on repair? Is it that big a deal?

GreeBo

Linto wrote: »

So would you insist on repair? Is it that big a deal?

things like insulation, air tightness, electrical protection, correct plumbing are all important that they are done correctly.

Some of them, if done incorrectly wont cause a disaster, but they will not perform as they are supposed to.

I would image in a couple of years you have a very cold section of wall where that gap is and possibly even damp issues.

If Im paying someone to do something like this (which, tbh is why I rarely every do, and just to it myself) i want it done correctly.

I would second the advice to get someone in who knows exactly how this stuff needs to be done and have them oversee each step. Otherwise you are in danger of getting an expensive job that looks right, but doesnt perform as it should for the cost. e.g you could build a 9 inch cavity block wall with no insulation and put some insulated plasterboard up for a lot cheaper and probably not notice much difference in the results.

Linto

GreeBo wrote: »

things like insulation, air tightness, electrical protection, correct plumbing are all important that they are done correctly.

Some of them, if done incorrectly wont cause a disaster, but they will not perform as they are supposed to.

I would image in a couple of years you have a very cold section of wall where that gap is and possibly even damp issues.

If Im paying someone to do something like this (which, tbh is why I rarely every do, and just to it myself) i want it done correctly.

I would second the advice to get someone in who knows exactly how this stuff needs to be done and have them oversee each step. Otherwise you are in danger of getting an expensive job that looks right, but doesnt perform as it should for the cost. e.g you could build a 9 inch cavity block wall with no insulation and put some insulated plasterboard up for a lot cheaper and probably not notice much difference in the results.

Great advice. Thank you!

maddragon

Sorry,
But the workmanship displayed in that one photo is just sh1te as mentioned earlier. There are enough excellent unemployed builders around the place at the moment that this sort of thing should not happen. You know yourself it's sh1te or you wouldn't have sent the pic.

sydthebeat

the problem with the insulation aside, that photo makes no sense to me.

If its a jamb of an opening what the hell is that block doing in the middle of the cavity??

Theres 4 or 5 pieces of evidence in that photo alone that tells me the block layer either doesnt know what they should be doing properly, or doesn't give a damn.... i really hope thats not a reflection of the rest of the blockwork

1. the mortar application is terrible
2. the block in the jamb is not returned from the inner leaf
3. the thickness of the returned block is all wrong, 100mm is standard, but best actually left out.
4. if thats a 60mm insulation board theres no way 40mm cavity is left.
5. the mortar snots are an indication of terrible workmanship
6. ive no idea what the string line is doing there

11wingnut

http://youtu.be/NpkXxHRp8U0 check this out it is part of a 2 part .no gaps near enough is not good enough .this is different insulation but the theory
is the same .

BarneyMc

I would be worried about moisture (as well as heat) crossing this mortar bridge and causing dampness. It's not surprising pumped beads are used by some instead.

esox28

If you dont raise this issue with the blockie he will continue with that standard throughout the build, imo yo6 need to choose your battles but calling his attention to this workmanship early on in the project wont effect your working relationship but sets out the standard you are looking for.

Water off a ducks back....he not nessarly a bad blockie but some guy dont pay any attention to insulation, why would they no engineer ever pulled them up on there shoddy misfitted insulation not to mention the fact they dont clean snots off internal cavity to insure snug fit to internal block.

You need to be confident in you approach, " Im keen to have insulation tight to internal block and no gaps" simple as that maybe.

My main point being be confident and ask loads of questions your the principle contractor on the job the boss end of.

Im not an engineer but im selfbuilding at the mo and just offering my experience, keep posting the main posters here helped me no end.

kawasaki1100

Linto wrote: »

Hi guys,
The builder started building the extension today (cavity wall). I had a look this evening and notice a slight gap in the insulation (see picture attached). Is this something I should insist on having corrected or is a small gap like that normal enough?

(I don't want to create any unnecessary agro)
Thanks!

Yep,its crap construction alright. As other posters have pointed out you should not have any gap in the insulation, the tounge and grouve insulation joint should fit neatly together. I shudder to think what else is going on that you cant see.
As another poster correctly pointed out regarding the transfer of moisture on the mortar accross the cavity due to the bad workmanship and no attention to detail, this will also cause a cold bridge also accross the cavity and will cause mould to form on internal finished walls. You should urgently have a word with your builder before any more disasters occour and employ an engineer to oversee your works:)