Staple-up radiant heat under Advantech subfloor.
Owner chooses plainsawn SYP t&g 3/4″ wood flooring in 5″ width. Oil-based polyurethane finish is done on site, one coat after laying and sanding, two more coats after finish work and painting complete.
Two winter heating seasons later, owner is upset about excessively large shrinkage in boards, showing cracks as wide as 1/2-inch. Wants a fix, probably a rip-up and replace, at least in the rooms where the shrinkage condition is worst.
Not my job, but that of a friend, so I don’t have all the facts, but I know the radiant heat wasn’t on before the flooring went down, and that the flooring sub didn’t use a moisture meter to check things out.
Gene Davis, Davis Housewrights, Inc., Lake Placid, NY
Replies
Your answer will probably end up between the flooring installer and the HVAC guys who designed the radiant floor system and controls. Maybe ultimatley with the GC who should have known better.
If the SYP was anything much over 10-12%, it probably would have opened up even with forced air, unless extensivly humidified.
If the radiant floor system was slapped in without a heat loss calculation and control strategy that would heat the place comfortably with 85* floor temperature or less, then it would make the shrinkage worse
I've lived with maple floors (read "prone to alot of seasonal movement") in two houses, one with high heat loss and forced air, and one with extremely low heat loss and well-designed radiant sandwich. Guess which floor shows almost NO seasonal movement? Of course, for the second one I paid alot more attention to moisture and acclimation.
Edited 6/29/2005 3:30 pm ET by johnnyd
I think your answer is right in your post.
If the flooring installer didn't bother to check the wood to see how dry it was, then he/she was installing blind. Furthermore, it is my understanding that the underlying heating system has less to do with the shrinkage than the wood humidity at the time of install, the species, and the cut through the wood.
Obivously, narrow planks of stable wood that are arranged end-grain up (rare but very stable) or quartersawn (much more common) are the ideal radiant finished flooring surface. However, even wide boards consisting of species that like to expand and contract a great deal with RH changes can be accomodated via a floating floor design. However, such floors take more skill and time than the regular kind...
So, unless the flooring installer has a signed disclaimer from the GC in his hand that acknowledges that the GC made him/her install the flooring despite it not being seasoned enough, I would argue that the flooring installer is at fault here. However, it also sounds like the house is suffering from wide swings in RH, which is an issue I would also address before putting in a new floor (if that's what it comes down to) or to install a floating floor.
If the flooring had the correct moisture content in it to begin with, the shrinkage would not have been so excessive. I saw a similar oak flooring installation with gaps that large, but everything that should have been done correctly for a good floor installation was not done. When the floor heat came on the first season the gaps appeared, the gaps would have appeared sooner or later. I measured the flooring after it "shrunk" it measured exactly what is should have been. The flooring was put down with an excessive moisture content.
I have similar flooring and heat and have no shrinkage or gapping issues, I made sure the climate and conditions were optimal for installation.
The radiant heat should have only a very small effect. The flooring must have been pretty moist to have opened up a half inch gap. I hope that the whole floor is not like that.
We tell all of our customers that solid wood flooring of any width will have some seasonal gaps unless the inside humidity is controlled year round. The wider the boards, the bigger the gaps and the gaps will not be uniform. I am now looking at my own floor, twenty year old plainsawn red oak. In the humidity we have been having over the past month, most of the gaps have closed up. Last winter many of those boards had a sixteenth inch gap, particularly those above the wood stove.
It sounds like your friend has a different situation on his hands. I hope that he can work something out, at least get the worst areas fixed.