Cause of cracking butt joints?

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Posted by: from Barrie
1/24/2015 at 8:59:33 AM

Hi guys,

I have a client who wants me to fix his ceiling in his basement. It is a boarded, flat finish and I have found that the butt joints are cracking where it is taped. Now the floor joists are 2 x 8 and approx 12 feet long, (from outside wall to where the post are located). The house isn't very old.

What could be causing this, and what is the best method to repair this?

Thanks guys. Have a good day.


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Date/Time1/24/2015 at 10:34:58 AM


The cracking is probably caused by the floor movement. The span (joists) from the outside wall to the center beam is stable at the wall side but the inside end of the joist has settled. I think the inside is resting on a beam, supported by teleposts. If this is the case, the teleposts should be adjusted so the flooring (sub floor) doesn't "bounce". Sometimes the center beam settles just a little, that is allows for floor vibration. Also, check the ensure the sub-floor is still attached to the floor joists.

Hope this helps.


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Wesley from Weswal Interiors in Toronto
Date/Time1/24/2015 at 10:44:09 AM

There are a few reasons.

1.) If the joint does not have enough screws, when someone walks around upstairs the joint will move and crack. Adding more screws on each side of the joint will certainly help, and then re tape the joint.

2.) Another reason is if the previous taper used fibre tape on the joints along with regular compound. With fibre tape a product called sheetrock 90 or 45 or 20 must be used on the first coat in order to avoid cracking. The numbers correspond with the products drying time. On the second and third coat you can use regular compound.

3.) Also a factor is the age of the home. If the home is less than 1 year old, the builder should have informed the homeowner that they should not have done anything for the first year. Two reasons for this is because a.)your homeowners warrantee is usually for the first year and if there are issues the builder is responsible, b.) the home will settle so there will be movement which will cause stress on any of the joints and can cause cracking.

I hope this helps.

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Joel from Rise Renovations in Windsor
Date/Time1/28/2015 at 11:02:30 AM

I agree with Wesley.

It is most likely that the butt joints either:

- Have come loose from movement from the floor joists

- There wasn't enough screws holding it in place (minimum of five screws)

- The installer put the screws in too deep breaking the paper

- Or worse, if the drywall was installed perpendicular with the floor joist, and the butt joints didn't land on a joist.

Many reasons why this may have happened. There are two ways of fixing this.

1. Screw at least five screws on each side of the joint, making sure there is proper backing to hold it in place. And re-tape it.

2. Take everything down, strap the ceiling to minimize movement to the drywall, and board and tape.

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