Cracked Subfloor

[Rauch0812]

We just purchased our first pop up.  It's a 2000 in great condition, except for one thing... there is a soft spot in the floor.  When you crawl underneath the camper you can clearly see a two foot crack in the subfloor.  Like maybe a child jumped off the bed?  I hate to rip up the flooring inside as it is still in excellent condition.  We were considering trying to somehow brace the floor from under the camer, but we're not sure what to use or what to secure it to.  Can we place another board underneath and put screws up through the boards? Does anyone know how thick the floor is (or how long the screws could be)?  Would this even work?  Any helpful ideas?  We could probably just leave it, but I'm afraid it will spread.  Any help would be greatly appreciated!

Des

[wavery]

We just purchased our first pop up.  It's a 2000 in great condition, except for one thing... there is a soft spot in the floor.  When you crawl underneath the camper you can clearly see a two foot crack in the subfloor.  Like maybe a child jumped off the bed?  I hate to rip up the flooring inside as it is still in excellent condition.  We were considering trying to somehow brace the floor from under the camer, but we're not sure what to use or what to secure it to.  Can we place another board underneath and put screws up through the boards? Does anyone know how thick the floor is (or how long the screws could be)?  Would this even work?  Any helpful ideas?  We could probably just leave it, but I'm afraid it will spread.  Any help would be greatly appreciated!

Des

The 1st thing that you need to determine is if there has been water intrusion into the floor. The floor is made of a wood composite and if it has had any moisture in it, screws will not hold. Also, there is a good chance of wood-rot. Saying that the floor is "Soft" is a sign of rot.

Take a screwdriver and poke around to see if the wood on both sides of the crack is hard and solid. If you can poke the screwdriver into the wood, replacement may be in order.

If you want to just brace up what's there, you could use some 5/8" plywood. Cut it to fit from one frame member to the next then pop-rivet some 1" angle iron into the frame, under the new plywood to brace it in place. You could also put some 1" long drywall screws up into the original floor, wherever the wood is solid.

[ScouterMom]

Same as Avery said above - except that if you don't want to screw into the floor (not sure how thick it is, and don't want to come up thru the linoleum) you can GLUE a board underneath and it will support just fine.  I like gorilla glue - but you have to clamp it, or put pressure against the piece you're glueing, at the glue foams and expands a bit - to grip really well.

[wavery]

Same as Avery said above - except that if you don't want to screw into the floor (not sure how thick it is, and don't want to come up thru the linoleum) you can GLUE a board underneath and it will support just fine.  I like gorilla glue - but you have to clamp it, or put pressure against the piece you're glueing, at the glue foams and expands a bit - to grip really well.

In the boating industry we called that "Screwing & Glueing". You should be safe using 5/8" ply and 1" screws. Your floor should be 5/8" and surely a minimum of 1/2". But "Screwing & Glueing" is an excellent idea. The screws act as your "clamps" while the glue dries.

[Old Goat]

In the boating industry we called that "Screwing & Glueing". You should be safe using 5/8" ply and 1" screws. Your floor should be 5/8" and surely a minimum of 1/2". But "Screwing & Glueing" is an excellent idea. The screws act as your "clamps" while the glue dries.

Wavery,

Please explain to me how a 1" drywall screw, which you recommended in a previous post, driven through a piece of 5/8" thick plywood and into flooring which is probably OSB board to a depth of 3/8" will "clamp" or hold anything. Even regular 1" coarse thread wood screws placed in predrilled holes in 5/8" plywood  only leaves 3/8" of the screw to be driven and there will be no holding power regardless of what it is driven into, because the end of the screw is tapered..

A far better idea would be to cut the plywood to size and then place it over the damaged floor area on the under side and mark it's position around all four sides. Then apply contractors adhesive or liquid nails to the marked area and side of plywood for a thickness of about 1/16" on each surface. After the piece is in place, it can be held in place and pressure applied by precut scrap wood props like 1 X2"s etc. Gorilla glue is fine but it gets very hard over time and is very expensive. Contractors adhesive [Lowes or Home Depot] is not expensive and it never gets brittle which will allow it to flex and not come loose with the floor movement during use and travel...

PS,  My father was a well known boatbuilder in south Florida and I spent a lot of years in design, engineering, construction and repair of boats and yachts.

[Bluedog225]

I would handle it this way assuming there is no soft wood (if there is, you need to ID the source of the leak and fix it first, then decide whether to replace flooring).


-Cut an oversized piece of exterior or marine grade plywood to cover well beyond the damaged area.  The bigger the better (within reason) except that it increases the amount of glue needed and the weight of the repair

-Coat the not to be glued side and the edges with 3 coats (first one thinned by 50%) of spar urethane.  When it dried, remove any dried drips of urethane on the uncoated side that will keep it from mating with the floor.  

-Use a good adhesive (I would use epoxy (expensive) or tightbond II or III (cheaper)).  I agree that flexible may may be better.  I had a bad experience with liquid nails and don't use it anymore.  That was back in 1995.  Others have had no issues.

-Apply glue, use liberally around the outer edges and criss cross through the middle if the area is too large to coat entirely.  The outer 4-6 inches need to be coated without gaps.

-Push up into place with a couple of bottle jacks and 2x4s to distribute the pressure.  Push up enough to squeeze out a little glue all the way around but don't push so hard you squeeze out all the glue.  You just want to eliminate gaps.  Check all the way around before leaving to dry.

-If you use epoxy, it will tell you how long it needs to cure.  Leave woodglue on much longer than you think you need as sometimes, with a big, closed off,  application like this, the interior stays wet for a while.

Good luck.

Tom

[paul_b30]

We just purchased our first pop up.  It's a 2000 in great condition, except for one thing... there is a soft spot in the floor.  When you crawl underneath the camper you can clearly see a two foot crack in the subfloor.  Like maybe a child jumped off the bed?  I hate to rip up the flooring inside as it is still in excellent condition.  We were considering trying to somehow brace the floor from under the camer, but we're not sure what to use or what to secure it to.  Can we place another board underneath and put screws up through the boards? Does anyone know how thick the floor is (or how long the screws could be)?  Would this even work?  Any helpful ideas?  We could probably just leave it, but I'm afraid it will spread.  Any help would be greatly appreciated!

Des

I am in the construction business and this is how I would fix it.

-cut a piece of Aspenite 5/8 of an inch thick
- use PL premium construction adhesive. (this is water resistant and extremely strong, landscapers use it to hold retaining wall blocks together)
- have someone hold it in place while you screw it to the floor with long flat head screws FROM THE TOP.
- then you can install a new very inexpensive vinyl tile floor over your existing floor in order to cover the screw heads.
- I would finally cut the extra length off the screws at the bottom and spray your new patch and possibly the rest of the floor with a rubberized or asphalt undercoating from your local car parts store. This will prevent water damage when pulling the trailer in the rain.
I recommend Aspenite because it is engineered to be strong and more moisture resistant than regular plywood, plus it's way cheaper. Aspenite has a smooth side and coarse side one of these sides actually has a thin wax coating to repel moisture and is usually marked "This side out"
I know you were probably not looking at doing a new floor - but in my opinion screwing from the top is your only and best option. The chipboard is not thick enough or strong enough to support with screws with only 1/2 inch of penetration - plus this method will only weaken with time and use.
Paul.

[wavery]

The concept of "Screwing & gluing" is that the adhesive is what is really doing the work. The screws are merely acting as a "Clamp" until the glue dries. Which direction the screw is driven is immaterial. Once the adhesive cures, you can remove the screws. They aren't doing anything at that point. So to answer Rauch0812's question......yes......it can be done the way that you are suggesting and it will be stronger than it is currently IF the current material is sound and not water damaged.

The proper procedure would be to remove the cabinetry and replace the effected wood as necessary.

My post was directly responding to the OP question as stated. Any of these methods would be better than what he has now. None of them are the "Right way" to effect the "proper" repair.

[austinado16]

Screwed & Glued works great, and that's exactly how I'd patch this.  Simple, inexpensive, won't take you much time, and will be stronger than the original floor.

Think about how a glulam beam is made.......glue, strips of wood, clamped together until dry.  Much stronger than a beam made of solid wood of the same dimensions, and cheap to make.

I would make the patch piece as big as you can fit into the space.....so yes, run it frame member to frame member for maximum coverage/strength.

I'd pre-drill holes in the patch so that your screws can glide through it, but do all their work gripping into the camper's floor.  I'd use counter sunk head screws so they'd give that wedge grip as the head sinks into the patch.

The PL construction adheasive is super strong, real wood glue is super strong, but Gorilla Glue is just insane.

Do yourself a favor and nip the tips off your screws with a pair of dykes so that they can sink fully into the camper floor, without the chance that their points come poking up through.  You can figure out how thick your floor is by crawling under the camper and looking for where the propane lines or electrical wiring goes up through the floor.  Use a pin, or a nail to go up into the hole......have a helper tell you when the tip pops up into the camper, and then put your finger nail against the pin/nail, flush with the underside of the floor and pull the pin/nail back out.  There's your story stick for how thick the floor is.  Buy screws and trim their points accordingly.

Do not coat the underside of the floor.  It needs to breath or it will rot. That's why none of the camper manufacturers coat their undersides.

All that being said, as Wavery originally suggested, figure out if you've got a water leak, and rotting floor.  You don't want it spreading and getting worse...and it will.