Is this to be expected ?

[wanleg]

Had two storey extension on house which started late July and finished early Nov. All of the plaster on the stud walls (stud walls only externals are fine) have blown the plaster in the corners as per the pics. This has happened both upstairs and downstairs, on ceilings and on walls. Is this just the result of the plaster / stud work timber drying or is it some other issue ?

Cheers
George


View media item 18589
View media item 18590

 

[patcher]

Looks to me to be a very bad case of shrinkage. Is there any scrim between the ceiling and wall joint? Was the surface the plaster applied to really wet before the finish went on?

 

[roy c]

Yes it looks like there may not be any scrim tape between ceiling and walls. Also what size joists were used for upstairs floor and down stair ceiling? I would get someone to walk around up stairs while you stand below and check for any movement...

 

[wanleg]

Looks to me to be a very bad case of shrinkage. Is there any scrim between the ceiling and wall joint? Was the surface the plaster applied to really wet before the finish went on?

I honestly don't know, the plasterer was working whilst I was away at work etc...

I'm guessing wait for the shrinkage to stop then sand and fill to sort this ?

 

[wanleg]

Yes it looks like there may not be any scrim tape between ceiling and walls. Also what size joists were used for upstairs floor and down stair ceiling? I would get someone to walk around up stairs while you stand below and check for any movement...

Again as per the previous post I don't know any of the specifics....I will do the walk test though. The extension was undertaken by a local (just up the road) builder who does a lot of work on our estate....we have three separate friends on the estate who have undertaken extension work on the same type of house as ours with no problem by this builder....but as I say I will do the walk test anyway.

 

[patcher]

I'd be inclined to ask your builder back and have a look at the problem. If he's reliable then he'll be able to give to give you a reasonable explanation. Looks very much like to me the joist were wet when they were installed and now they have shrunk pulling the ceiling with them. This could have been avoided by making sure that joist were dry enough to be plasterboarded - not always avoidable - especially on tight deadline jobs.

The remedy is to:

1. Make sure joists aren't moving - walk test will do that
2. If the joists aren't moving - remove all the loose plaster and re-fill the holes left with new plaster or British Gypsum Easyfill (the plasterers version of polyfilla).

 

[wanleg]

Thanks for the replies.....in response to a previous post I can confirm that scrim tape was used on the joints....the missus remembers seeing the plasterer so this.

One other point that could also be valid....when extension was being built (and plastered) we had no heating....reason is is the boiler was in an old kitchen extension that was demolished to make way for new.....so walls were plastered and dried pretty much naturally bar the odd fan heater here and there.

 

[patcher]

Having no heating is not really be a factor in your case - this is only a problem if its near freezing - which by your timings it should not have been and the symptoms would look different.

The photos you have put up indicates that the problem is movement - either shrinkage from the joists drying out or the joists moving. If scrim has been used then really the plasterer has done all they can. Scrim will stop small amounts of movement but not all.

If you have done the walk test and the cracks are not significantly opening or closing then the joists are probably secure and my best guess its due to the joists shrinking as they dried out. This should not be a major issue - removing the loose plaster and re-filling should solve most shrinkage issues.

 

[Richard C]

Almost certainly shrinkage as has already been stated, most probably caused by using badly stored/wet timber for the joists & studding. Also, have a little poke around to see if there is much in the way of filler underneath those cracks. If the wall/or ceiling boards weren’t cut nice & tight & the gap between the two wasn’t filled before the scrim tape was put on, all that’s holding the 2 boards together is around 3mm of Multi which will crack & fall out. It shouldn’t be much of an issue to sort out but I would leave it until mid summer (assuming we get one) to give it a good chance to dry out or you could be wasting your time.

Drying out naturally is the best possible way of avoiding cracks so having no heating is not an issue.

 

[wanleg]

Definitely no movement when walked on from above plus the same problem has occurred on the ceilings on the upper floor.

I picked some of the plaster off.......could see the scrim tape quite easily....I think the paint makes it look worse than it is....one of the pics was from the downstairs toilet which has been painted with kitchen/bathroom paint, more of a skin really.

Thanks for all the replies.