Install hardwood on top of a old plywood subfloor
#1
05-14-20, 10:33 PM
Install hardwood on top of a old plywood subfloor
I have a old house. After take out all the old hardwood floor, we found the subfloor is thin 5/8" plywood subfloor above the crawlspace( no insulation) . the plywood wood piece has big gap between each piece. I can see through the crawlspace. Some wood piece have big or small hole, like quarter size .
We need to have 3/4" oak hardwood floors installed over this plywood subfloor. what kind of preparation I need do before install ( nail down)?
My concern is the moisture, bug or mice can get through the gap. Do I need to seal the gap and hole before put the underlayment? Do I need to add a layer of pressure-treated plywood on top of the subfloor first? or cork?
Any suggestion? Thanks.
We need to have 3/4" oak hardwood floors installed over this plywood subfloor. what kind of preparation I need do before install ( nail down)?
My concern is the moisture, bug or mice can get through the gap. Do I need to seal the gap and hole before put the underlayment? Do I need to add a layer of pressure-treated plywood on top of the subfloor first? or cork?
Any suggestion? Thanks.
#2
05-14-20, 11:48 PM
Member
Your flooring manufacturer will provide min recommendations, that would take precedence over any comment provided here.
Typ sub floor needs to be solid and secure 3/4" OSB or plywood.
As far as mice and non insulated area, that probably needs to be resolved and not necessarily just because of he flooring!
Typ sub floor needs to be solid and secure 3/4" OSB or plywood.
As far as mice and non insulated area, that probably needs to be resolved and not necessarily just because of he flooring!
#3
05-15-20, 04:39 AM
Member
#1, Never used pressure treated for underlayment!
The best way, but a lot more work and would not change the height much and the floors will be less likely to squeak would be to remove what's there and install Advantech T&G subflooring.
The second best way would be to just go over it with underlayment rate 1/2" plywood making sure the seams do not line up with the seams below, and fastening every 4" on the outside edges and from 6 to *8" in the field, making sure to never nail into the joist below.
Never use any glue between the layers!
The fastest way to nail it down would be with a pneumatic narrow crown staple gun.
The best way, but a lot more work and would not change the height much and the floors will be less likely to squeak would be to remove what's there and install Advantech T&G subflooring.
The second best way would be to just go over it with underlayment rate 1/2" plywood making sure the seams do not line up with the seams below, and fastening every 4" on the outside edges and from 6 to *8" in the field, making sure to never nail into the joist below.
Never use any glue between the layers!
The fastest way to nail it down would be with a pneumatic narrow crown staple gun.
#4
05-15-20, 05:11 AM
I went through a similar problem two weeks ago. After the fire I ended up with a builders subfloor (1/2" plywood) that was in very rough shape mostly from water damage. Seams were "soft" in places and the subfloor squeaked. We blocked all the seams from below and added a layer of 5/8" plywood on top of the original subfloor. This was the recommendation of the flooring installer. He then added a 15# felt layer between the new underlayment and the hardwood plank.
#5
05-15-20, 05:11 AM
Group Moderator
I would add a minimum of 3/8 cdx on top of the subfloor, screwed to the 5/8 plywood with 1 1/4" deck screws 8" on center. Then felt paper, then you are ready for flooring.
As for the crawlspace, at a minimum your floor should be insulated, and it would be wise to have the crawlspace encapsulated with a heavy poly vapor barrier. Then it should either be vented or conditioned. You don't want moisture from the crawlspace ruining your new wood floor.
As for the crawlspace, at a minimum your floor should be insulated, and it would be wise to have the crawlspace encapsulated with a heavy poly vapor barrier. Then it should either be vented or conditioned. You don't want moisture from the crawlspace ruining your new wood floor.
