Subflooring – What lies beneath?

The material placed on top of the floor joists may be plywood, Oriented Strand Board (OSB) or particle board. In any case the joists have glue spread on them and then the 4′ x 8′ panels of sub flooring are nailed in place.

At the time the sub floor goes down the bottom of the home has been assembled and is resting on its frame and wheels, but has nothing to force it to be square or straight. Since the floor panels are known to be square the house itself is squared up by forcing the joists and side edges to line up with the floor panels. This involves sledge hammers and come-along’s and can make for some ugly edges. However, if all else fails and there is still some overhang, a router will fix that.

The floor panels are nailed to the joists and edges with powerful air guns that will drive 4″ or 6″ nails at a rate of one or more per second. Needless to say, not all nails get driven straight or into the joists. In addition, the depth to which the nail is driven depends on the setting of the air gun. Too much power and the nail is driven well below the surface, to little power and the head sticks up. This can make for interesting problems for the carpet and vinyl crews.

{ 20 comments… read them below }
Nina
I would like to replace the original carpet in my 1997 single wide mobile home and noticed that you mentioned wood laminate flooring as the best option. Is this hard to do and can I do it without special consideration for it being laid in a mobile home? You talked about removing the carpeting and the walls being installed over the carpet edges, does this leave a mess? Why aren’t there any baseboards in a mobile home? Will I need to install baseboards if I put in laminate flooring? And, does the carpeting add to the warmth of a mobile home?
Thanks!

Paul
I actually built a site on installing laminate flooring and all the pictures were taken in a mobile home.
The original carpet is installed before the walls are set in place. If you cut it as close as possible to the wall with a razor cutter there won’t be any big mess. If the carpet has been replaced before there will be trim strips nailed to the floor that you will need to pry up. That is no big deal either.
Baseboard trim is expensive as you will find when you buy it to finish your laminate floor.
I guess carpeting has some insulation value. I suspect laminate with it’s backing has about the same insulation effect, Which is to say, very little.

Nina
Perfect, I just read through the installing laminate flooring page you mentioned… very nice! Love the suggestion of using a creeper; I can think of other household chores were that would come in handy! Now, to save the $$…
Thanks!

Nina
One more question… you said baseboard is expensive… can you use quarter round instead? What was used for the job shown on the “installing laminate flooring” page?
Paul
It’s a matter of looks. Quarter round would cover the gap as well as baseboard. The example site used the cheapest vinyl coated plastic they could find.

Linda
What shall I do ? I want to install a laminate floor in my manufactured home and some people tell me not to use a moisture barrier because their is already one under the house and I will create condinsation if I use one, and some say I need one … Help !!!
Paul
Follow the manufacturers instructions for installation of the flooring you buy and you should be fine.

Casey
How do I do about replacing floor joists on a 16 X 80? The whole outside frame needs to be replaced and some of the joists throughout also need to be replaced.
Paul
I think it is cheaper to find a different unit so I never tried anything that ambitious.

David Penix
Will I have any problems with cutting out damaged subfloor under the back door of my mobile home? to replace with new 3/4″ blywood? thanks
Paul
I suppose that depends on how good you are
Seriously, with the right tools and some skill it shouldn’t be a big deal. Just be sure to support all the edges of the replacement material.

Karl
I have some major water damage from a toilet supply line, and the flooring is warped. I have re-done my other home’s entire basement but do not have a lot of experience with mobile homes. Is the job of replacing all of the joists and subfloor in a mobile home difficult? Second wuestion, does my insurance usually cover this kind of thing? It just happened, and I am awaiting their response….Thanks!
Paul
You shouldn’t need to replace anything but the subfloor. The joists should be fine. I hate to predict what an insurance company might do these days

Jim_Vierling
Hello. I really, really wish that all of the sub floors that I have replaced had been put in with nails. I have found nothing but staples. 1 and 3/4″ staples that were put in by someone that had absolutely no problem with how many were used.
I have also come across different types of adhesives that were put on the joists. There is a brownish colored one, may have been a different color when applied, that is not much of a problem. Then there is the stuff that they used in my 1975 Vindale. It is grey and my jigsaw won’t cut through it without a lot of effort and it eats up the blades.
When I replace the old sub floors, I use either Elmer’s wood glue or Liquid Nails and screws. Construction screws are preferable. The screws make it much easier if you have to do it again in the future.
I do have a question and will post it in a reply to this post.
Paul

When you give a powered nail gun to minimum wage help and STRONGLY encourage them to work as fast as possible, using a few extra staples/nails is not a major concern

Jim_Vierling
I am replacing the floors in my sister’s 1982 Schult. What I have come across is that they have lowered the joists by 1/2″ where the seams of the sub floor panels come together. They did this so that they could add a 4″ wide piece of 1/2″ plywood on top of the joists. I guess this was done to make it easier to staple the ends of the panels together? They also heavily glued the top of the plywood piece so that it is a chore to try and get the sub floor off of it.
There are only two joists like this in the room that I am doing. Would it just be easier to cut out the old joists and put in two new ones? I am capable of hitting the joists where the panels come together.
Also, I am going to the trouble of cutting the ends of the panels that run across the joists in a pattern so that I can screw the braces underneath the edges into the joists directly.
That is just an idea for anyone having trouble bracing the edges.
To try and describe that: I measure the joists on center and then make cut outs every other joist space so that I can off set the braces underneath the panel. The cutouts only need to be about four or five inches in from the edge. Then the piece that butts up to that end gets the reverse cut outs in it. I also meant to ask if it is legal to not have hangers on the joists? None of the joists in my sister’s mobile home have hangers.

Tammy Horton
Trying to find out if a 1981 Fleetwood Broadmoor has plywood sub floor, never replace before. Thanks.
Paul
Hi Tammy,
As far as I know, plywood flooring was normally an extra cost upgrade. So the only way to be sure would be to pull back the carpet or flooring and look.
Paul

Click Here to Leave a Comment Below 0 comments