Glue Down Installation and Felt Paper
Q: Gluing wide boards makes sense, but is it effective if you have a layer of felt between the sub-floor and finished floor?
Jason S.
A: When gluing a floor you will need to glue the planks directly to the subfloor. The felt being used should be removed before gluing your floor down. If this is a wood subfloor, I would honestly suggest nailing or stapling the floor as these are far easier installation compared to gluing.
With a glue-down installation, you have much more to consider than nailing. You have to take much more time to allow the glue to cure and to ventilate out the vapors from the glue. You can only install so much flooring at a time with glue in order to ensure the glue cures properly. There is a certain depth of glue you must spread and a specific trowel size that must be used when applying the glue to your subfloor (usually 1/8″ square-notched trowel). Proper amounts of ambient humidity (30-50%) and heat (62-65 degrees Fahrenheit) must also be observed to ensure the glue will dry properly and form a solid bond. There is more that must be done, but this should give you an idea as to the amount of work involved in gluing a floor and that doesn’t include clean up afterward because glue is messy.
Felt paper is normally in place to make it easier to slide boards into place and to help reduce some of the potential squeaking noise that can come with having a wood floor, but in the case of glue the paper will actually ruin your installation. The reason why you need to remove the felt is th ensure the glue forms a proper bond between the flooring and subfloor, thus anchoring the floor in place. If you were to glue the floor to the felt it would not form a proper bond and the flooring would be able to move, which can cause a multitude of issues. As I mentioned with the depth of glue required, this depth will not be properly achieved with the felt in place, which brings even more headache.
Long story short – if you intend to glue down your floor, do not use felt paper or any other underlayment, glue the planks directly to the subfloor.