cracks in new float and set work but no coincidence but why?

[trowelmonkey1]

well finally finished the big job i was on (well big for me at least) 3 bedrooms and a good sized lounge, all taken back to brick as the original plaster had all blown, floated with hardwall and skimmed.

went back today to do a couple of additional jobs only to be shown that in each of the bedrooms on the external walls only, a horizontal crack has appeared 2-3 inches below the ceiling line and they are between 2 and 4 foot long, no coincidence me thinks but i don't know why it's happened.

Guy has had the loft above converted into bedrooms 4 years ago so initially suspected the kids running around upstairs but the floor upstairs is supported by steels, as is the roof so no weight on the external walls where cracks have appeared, bit of a head scratcher, he's tried filling one crack 2-3 times but it keeps reappearing.

i'll need to sort this at some point soon but for now i've told him to keep an eye on them and see if they get any worse for the time being, pointless knocking off the skim and re-doing if it's still cracking, so he's happy for the moment.

any ideas anyone?

Sorry to be absent for so long and come back with a biggy thanks in advance!

 

[roy c]

Are you sure when you took it back to the brickwork that there were not any cracks already there that you didn't notice? Could be some cracking along the brick coarse when they had the loft converted and you didn't see them!
I haven't used hardwall too often so I don't know too much about it's "properties" but my mate back in Birmingham did his whole house inside on brick walls and no cracking... Might be worth knocking a section out where the cracks are and if there are cracks then there 's your problem... Was there a wooden wall plate installed (2" to3" below ceiling)....

 

[roughcaster]

Are you sure when you took it back to the brickwork that there were not any cracks already there that you didn't notice? Could be some cracking along the brick coarse when they had the loft converted and you didn't see them!
I haven't used hardwall too often so I don't know too much about it's "properties" but my mate back in Birmingham did his whole house inside on brick walls and no cracking... Might be worth knocking a section out where the cracks are and if there are cracks then there 's your problem...

Was there a wooden wall plate installed (2" to3" below ceiling)....

I'm with you Roy and the wall plate question.

TM,, try "tapping" in a 2 or 3 inch nail,,,, about a half inch or so "above" the crack/s,,, you'll soon know if it's timber plate underneath the plaster. Don't tap the nail all the way in though,, will ya.

Roughcaster..

 

[trowelmonkey1]

Eureka!! god darn it why didn't i realise!

There was timber running across the tops of all the external walls, MUST be the cause!! i covered them in EML before floating but this obviously wasn't enough, the cracks only showed up over week after the rooms were finished though so why now chaps?

and more importantly how to remedy it?

thanks for the replies so far fellas!

 

[roughcaster]

The wood absorbs moisture from the plaster, and swells up,, shrinks back causing the plaster to crack. You did the right thing by covering the wood with EML, but it sometimes pays, to give any bone dry timber, a good continual soak, over a number of hours with a brush/spray, then put on the EML, plus pva,,, then scratch over it using hardwall/bonding,, leave it overnight to absorb the moisture,,,
the following day, dampen/pva, then float/finish the wall. You can even seal in old dry timber with a couple of thick coats of oil based undercoat, then put on the EML etc, anything to get rid of the absorbancy of the old wood,,, again,, scratch it in, and leave it overnight to expand, then plaster the wall.

What i'd do next??

If it is timber plate underneath the plaster, I wouldn't hack any of the plaster off if it's solid onto the EML,, leave it, as you said, to settle down,, then if it doesnt get any worse, rake out the cracks, and fill them up with a powdered filler/let it set,,,, then tape over them/sand them down. It's right at the top of the wall, so you'll easily tape the cracks and feather them away,,, you'll never know they were there.

Roughcaster.

 

[trowelmonkey1]

Thanks a lot RC!!

good to know i'd ALMOST done the job correctly, lesson learnt my friend, off to source oil based undercoats for next time, i did give the timber what i thought was a good drink but it was obviously thirstier than i thought.

thanks for your good and prompt advice as usual.

here's hoping it'll settle down and will be happy fine filled.

 

[Dario]

I may have some advice for you. My dad is using the plastic mesh. It is also good for that types of surfaces

 

[roughcaster]

I may have some advice for you. My dad is using the plastic mesh. It is also good for that types of surfaces

What is that your dad uses Dario?

Roughcaster.

 

[Dario]

It looks almost same as the metal one for rendering but plastic it will support the plaster about 1200mm wide. similar to jointing tape. Is in use also with external insulating

 

[roughcaster]

Thanks for the reply Dario. I've not seen that type of mesh.

Roughcaster.

 

[trowelmonkey1]

me neither Dario, any chance of finding the name? always good to find new products!

 

[1john]

This may be of help, i removed some old walls before which were timber with brick infill between them, rendered and skimmed. These were ripped down as the timber sole plate had rotten. However there were no cracks on the walls where the timbers met the bricks which suprised me but upon close inspection the people who did the rendering had nailed slivers of plasterboard over the timbers to over lap the edges of the bricks either side.

 

[trowelmonkey1]

ah, a neat little trick!

 

[roy c]

We also use slates aswell to cover the timbers...

 

[trowelmonkey1]

slates you say! another useful tip more likely to have plasterboard on my van though.