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strategery 11-03-2011 12:00 AM

cleaning up foundation walls for good foam board adhesion
Would it be a mistake to use a pressure washer to try to get the old chipping paint and debris off of my basement walls? I want the foam board to have a really good adhesion. I worry that the glue alone will not be strong enough.

I was told by a friend that I will regret bringing a pressure washer down there because water will get between the walls and will take forever to dry (I don't have a sump pump) even with a dehumidifier running.

In some areas the wall looks like it's bowing in a little but it is in fact the paint bubbling off. Some of the paint chips off easily with a putty knife. Most of it doesn't come off so easily. It's a lot of work.

What do you think?

Canucker 11-03-2011 08:32 AM

Get a wire brush and start scrubbing. Pressure washer is just a bad idea, if you want to see the results, open the door to your bathroom, run hot water to the shower till the tank empties without the fan on. Multiply by 10. that's what the pressure washer will do to your basement and house.
Once you glue the board to your walls, you need to mechanically attach it as well. Either build a stud wall against it or attach strapping through it and secure it to the concrete wall. Pressure washers are for outside.

Windows on Wash 11-03-2011 08:55 AM


Good stiff bristle brush and start hitting the walls with it.

You will be surprised how well the adhesives will bond as they will grab the irregular surfaces and hold the board to it.

You will need a mechanical bond as Canucker mentioned too.

algored2deth 11-03-2011 11:59 AM

Also make sure the paint does not have lead in it. Maybe you have checked but if not, do so. It will change your strategy here. Otherwise, the other's ideas are good starting points.

strategery 11-03-2011 04:56 PM

Thanks for the help, guys. I will go to home improvement store and pick up a brush tonight. Hoping to get this project done and have the insulation up before december.

One more question. I don't know much about the mechanical fastening aspect of this job. What kind of strips do I need to be looking for that will be good to work with? Is there something specific I need to ask for or use?

ajamison 11-04-2011 07:52 AM

I used masonry nails with large washers, then taped over the nail/washer when done with foil tape. I had to use a 2lb hammer to drive them in.

TimMauriello 11-04-2011 09:08 AM

Do you plan on framing walls in front of the foam board? If so, if you frame tight to the insulation you'll be fine and wont need to screw or hammer it in.

If not, you now have another issue as foam board isn't supposed to be left exposed as its a fire hazard. You'd have to look into local codes on that. If its for a mostly unused space, you are probably safe, just could have inspection issues down the road...

ajamison 11-04-2011 12:05 PM

Or you could use Thermax - foil faced, so it doesn't need to be covered if basement is to be let unfinished.

strategery 12-02-2011 01:01 AM

Well, guys, my situation isn't looking too good right now.

I bought a wire brush a week ago and started cleaning up the walls as best I could. It's really a tough job.

I started in a small area and I attempted to glue a half inch foam board to the wall and I just can't get it to adhere. I used a foam board adhesive glue applied by a caulk gun and I used the entire tube just trying to get a small area to stick. No luck. I tried pressing hard against it and leaning against it but it's not working.

What would be the next best bet? Do I need to drill some pilot holes then drive some masonry nails through the wall to get it to stay?

Windows on Wash 12-02-2011 06:29 AM

sounds like a 2 person job now.

Hold the insulation up, hammer drill, and screw the 1x4 sleepers through the foam into the wall with masonry screws.

joecaption 12-02-2011 07:05 AM

What is it your really trying to achieve with this project? If your looking for a finished basement then there's far simpler ways to do it.
Just build a wall at least 1/2" away from the outside wall using pressure treated lumber as the bottom plate and insulate with fiberglass made just for basements.
Two reasons paint comes off basement walls, wrong paint, moisture coming in from outside.
If the basement damp then trying to do anything on the inside will fail.
It needs to be addressed from the outside first.
Working gutters with down spouts far away from the foundation.
A french drain.
No flower or mulch beds up againt the foundation.
Grade slopes away from the house.

strategery 12-02-2011 05:13 PM

Not trying to finish it, just insulate the walls for improved comfort and to prevent energy loss.

Can't finish the basement because not enough clearance.

TimMauriello 12-03-2011 05:47 PM

Then you may get the most bang for your buck just insulating the rim joists area.

But, to hold the foam up, you could just put a pt 2x4 on the floor to hold a tight, slip the foam in behind that, than screw a 2x4 right in front of it at the top right into the joists to hold it in. Basically just the bottom and top plat of a wall.

strategery 12-14-2011 02:46 AM


Originally Posted by Windows on Wash
sounds like a 2 person job now.

Hold the insulation up, hammer drill, and screw the 1x4 sleepers through the foam into the wall with masonry screws.

When I drive the masonry screws through the foamboard and into the foundation wall (red clay block), do I want to drive through at the mortar line? Someone suggested I do that to avoid cracking the brick.

cbaur88 12-14-2011 08:12 AM

That might be a good tip but I think by pre-drilling the holes will eliminate most of that threat.

I'll be doing the same thing soon, however my wall foundation in my crawl space is cinder block w/ no paint to worry about. I am researching the best way to adhere the foam board to my walls as well. I don't see adhesive working that great simply because my walls are not flush flat and they might be too cold. There is excess mortal sticking out in many spots. I suppose I can chip that off but would like to get the best adhesion possible but need advice on what types of screws, nails, sinkers, etc... to use.

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