My house was built in 1952 and has radiant heat in the ceilings. All ceilings have cracks along the plaster board seams. What is the best way to fix them so they stay fixed? Should we tape and spackle (knowing heat will contract & cooling expand the surface) or should we experiment with caulk in the seams since caulk handles temperature fluctuations quite well. Or is there another solution? Thanks.

I've heard that this is (or can be) a problem with radiant ceilings, so can anyone with experience in this area comment?

-Darryl

I have radiant ceilings which are plaster.Although I have not experienced cracking in the tubing area I did have some normal hair line cracks which ran down through the middle of the ceiling in my larger rooms 15'x 36' and a 15'x 20' room. these were do to normal expansion contraction stress. All I did was use mesh drywall tape over the crack and topped it off with drywall compound don't use the light weight stuff. For extra measure after tapeing was done I used crack seal comes in a spray can, basicly it is a rubberized coating that expands with the crack and is paintable.Lowes,Menards,Homedepot carries the stuff.I have not seen any cracks yet been 3 years now.

I use mesh first, then cover with durabond (this stuff gets hard as a rock), then spackle with alittle dishwashing liquid in it. ceilings historically crack. in certin rooms i sheet rock over the plaster and leave a gap (especially if you have molding), about the width of a spackle knife, then cover the bare ends of the rock with a j molding (clean look). This gives a dimensional look, then paint with white with an off white in the channel left next to the wall. BoC

Ah yes Dura bond by Bondo I have used that outside on wood good stuff,work fast though or back off on the catalyst it was 90 ish out when I was using it first batch I tried was a little hot got hard about 3 min after I made the trip up the ladder.I will have to give it a whirl sometime on plaster.

The durabond I was speaking of is a concrete type product. you mix it with water. The only thing about it is, it gets as hard as a rock. Very hard to sand. You must make sure you only put enough on to make a base coat. BOC

The problem you are dealing with is called "calcification". That is the driving of a water molecule out of the gypsum based plaster. This occurs at surface temperatures above 120 degrees F.

Many ancient radiant ceilings operated at temperatures that were unecessarilly high. The heat output of a radiant ceiling is so high at moderate temperatures that it can usually handle the load very easilly below 120 degree F supply water temperature. They didn't know this back in the "olden days". You need to install some sort of tempering device to cut the surface temperature down to a more moderate level.

As always, you can contact me directly at tom@tesmar.com for more specific information.

good luck,

tom

I am working on a house that has radiant heat in the plaster ceilings. All of the ceilings have various cracks, especially down the middle. Other contractors have respackled the cracks only to see them return. Is there a permanent fix...would an elastomeric coating be of any value? Looking for answers if there are any...thank you in advance...

A little diversion from this topic, has anyone put a new pex radiant in a ceiling. I have a new house with an open attic, and sorry almost no insulation, for now. I have old plaster ceilings is this viable to install above?

I had a minor crack down the center of my radiant ceiling, the two rooms were 15' wide crack running longitudaly. I used mesh drywall tape and really feathered it out.

Gordy