Crack in newly plastered wall above window...

Rmgcook12 · 8 Jun 2014

Hi all,

I'm in the process of having a 1920s semi renovated.

The plasterer is currently working his way through the house. A week ago I had the lounge plastered. I had pulled off all the loose plaster, and it has been filled where needed to the original plaster and then the whole room covered in blue grit and skimmed. Inside side / top walls of the window opening have been plasterboarded then skimmed.

The plasterer was back this weekend to start work upstairs. Midway through the day yesterday he noticed a 1mm crack in the new plastered lounge, around 2-3 inches from the top of the window, running for around 2 feet (window is almost 8 feet wide). He had checked the edges first thing that day and didn't think the crack was there. I noticed that the plaster above the crack appeared dry (white), but below it was still drying

He was surprised to see it there and have me two possible reasons..

1 - that the crack had appeared because he was plastering to the original plaster, but he was surprised it had cracked so quickly if that was the case.

2 - this sounded more worrying to me... That because he had been working in the room above, and he is quite a sturdy built guy, that there could have been a fraction of a movement in the windows timber lintel from the floor joists above where he was working.

Has anyone ever heard of the latter happening, and if so now significant could this be?

I had the property surveyed before I purchased it and structurally it was reported back as sound (not that they could have seen this I appreciate). The plasterer said he hadn't notched any obvious issues when he saw the lintel prior it plastering.

I'm a bit worried that if it's serious - worst case could be fitting a new lintel? Given the newly plastered room and renovation budget fast diminishing - I really hope I don't have to consider this..

Views would be appreciated! I will try post a picture later on today when I go over to the house.

Thanks
Robin

roy c · 8 Jun 2014

First of all I would go in the room above where the crack is and walk around in the area and see if there is any "give" or movement in the floor boards. If there is any deflection then there might be some rot or wood worm in the joists or they might just need packing up. Have a look outside in the area above the window get a ladder up if possible and check for any cracks or hairline cracks, take a bit of time doing this and if it is plain render spray some water on (with a small spray bottle) around the area and see if any cracks appear as it dries out. I have never used blue grit so I cant comment on it but when I am over skimming old plaster I put 4" scrim tape over all the cracks and a strong coat of sbr or unibond over the whole of the wall. I let that dry out and when I come to skim I roller another coat over it and skim when its tacky. I have just discovered in my own bedroom I did a few months ago a hairline crack appearing which I must of missed when I prepped the wall. So it can happen to anyone really. Try to get some pics up of the areas where the cracks are and also some close up ones of the outside area around the window lintol. Its not the end of the world, I know it is disheartening but all things can be rectified

Rmgcook12 · 8 Jun 2014

Thanks for your advice Roy.

I'll take a look outside the house today - it's cement rendered and painted, so I'm not sure if that makes it harder or easier to spot cracks.

The floor boards are a little deceiving at the moment - I had the place rewired do but the sparky didn't screw all the boards back down as he knew the heating engineer would be taking them back up again (think that was a bit of an excuse myself!) - so they will feel a little loose. I might try get a couple up to look at the joists.

The plasterer did mentioned using skrim over the crack to sort it - but also suggested leaving it whilst he's working upstairs for a while to see if anything else develops (hopefully not!)

Thanks
Robin

roy c · 8 Jun 2014

Did your plasterer scrim tape the plasterboard he put in and any other old cracks in the old plaster? As for the floor boards being loose just take a few up by the area of the lintol and stand on the joists and see if there is any movement.. and get a thin screw driver and push it into both sides of the lintol where it goes into the wall to see if the wood is rotten.Also when you are looking at the lintol from outside on a ladder give the render a few gentle taps with a hammer around the lintol and see if it sounds hollow. If there are any cracks then water would be getting in and rotting the lintol.

Rmgcook12 · 8 Jun 2014

Hi

I don't think he plaster boarded where the crack is, but from memory it was around the area where the old plaster finished.

The area above the crack seems dry and below was still drying - I'm guessing perhaps the bond between the two wasn't very strong. As for why it's actually cracked though - I'll see what I can find under the boards. I can't see the lintel from the lounge as it's plastered now, or exterior as it's rendered. But I'll check for cracks when I go round shortly

JohnD · 8 Jun 2014

photos?

Rmgcook12 · 8 Jun 2014

Here are some photos.

A close up and far away internal shot to give you an idea - this happened a week after plastering. I've included an external photo - difficult to make out the crack. but its higher up the wall (a foot or so, roughly in the middle) than the one inside the property.

I checked around the outside of the property and there are hairline cracks in the render - not just above this window but also in other places.

I checked the adjoining house (not currently lived in) which had more cracks than mine. I also spoke to another neighbour who has lived on the street for 10 years+ to see if he had any cracks - he said that he did have a few around the render, and that another nearby house had been totally re-rendered because they had so many.

He seemed to think it was nothing to worry about and many of the properties were similar.... I hope there's some truth in that! I'm just surprised the new plaster has cracked so soon?

I'm sure that the location of the crack is roughly where the old plaster ended - you can see that the plaster below the crack isn't fully dry yet.

At the end of the day it's over 90 years old so I'm expecting cracks from settlement - I just want to be sure it's nothing more than that.

Didn't have chance to lift up any floor boards today to check the joists..

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roughcaster · 8 Jun 2014

In my opinion, it's what you said, the crack is where the old plaster ended, and the new plaster has been brought out flush, "the joint". The new, deeper plaster along the top of the window has cracked because it has not bonded to the edge of the orignal plaster. It's because of poor prep. When you join new plaster to old, prepping the edge of the old/original plaster is the most important bit of all. The edge, plus any brickwork/lintel must be cleared of any loose bits of plaster/dust. It must be then be given a wet down, and PVA brushed over it, paying "special attention" to the "edge/s". The area must then be plastered onto right away, while the whole area is wet/tacky, that way, the undercoat plaster will bond to the whole area, especially the edge of the original plaster. I think it's to do with the lack of prep in this job,,,, that's my opinion.

Rmgcook12 · 8 Jun 2014

Thanks roughcaster - I think it's that too. Plasterer is back at the end of the week so will sort it then.

pp23 · 20 Oct 2014

Rmgcook12 said:
Hi all,

I'm in the process of having a 1920s semi renovated.

The plasterer is currently working his way through the house. A week ago I had the lounge plastered. I had pulled off all the loose plaster, and it has been filled where needed to the original plaster and then the whole room covered in blue grit and skimmed. Inside side / top walls of the window opening have been plasterboarded then skimmed.

The plasterer was back this weekend to start work upstairs. Midway through the day yesterday he noticed a 1mm crack in the new plastered lounge, around 2-3 inches from the top of the window, running for around 2 feet (window is almost 8 feet wide). He had checked the edges first thing that day and didn't think the crack was there. I noticed that the plaster above the crack appeared dry (white), but below it was still drying

He was surprised to see it there and have me two possible reasons..

1 - that the crack had appeared because he was plastering to the original plaster, but he was surprised it had cracked so quickly if that was the case.

2 - this sounded more worrying to me... That because he had been working in the room above, and he is quite a sturdy built guy, that there could have been a fraction of a movement in the windows timber lintel from the floor joists above where he was working.

Has anyone ever heard of the latter happening, and if so now significant could this be?

I had the property surveyed before I purchased it and structurally it was reported back as sound (not that they could have seen this I appreciate). The plasterer said he hadn't notched any obvious issues when he saw the lintel prior it plastering.

I'm a bit worried that if it's serious - worst case could be fitting a new lintel? Given the newly plastered room and renovation budget fast diminishing - I really hope I don't have to consider this..

Views would be appreciated! I will try post a picture later on today when I go over to the house.

Thanks
Robin

looking at your pictures its down to the preparation not plasterers fault nor due to movement take it off and re do . it is down to old house and poor resources very rectifiable

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Crack in newly plastered wall above window...

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