Need advice on surface prep for residing in Vinyl


Old 04-30-11, 03:59 PM
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Need advice on surface prep for residing in Vinyl

I own a home built in 1975...2 x 4 studs 16 o.c. My home has sheeting that has been referred to as "Buffleboard"...from the inside of my unfinished garage, it looks very dark brown and for lack of a better description "hairy" if you drill a hole in it. I'm not sure if I have the correct name for the product. ANYWAY...I have hired a contractor to take my old masonite siding off and I'm going to reside with vinyl. They plan to put a product called "Fan Fold" which is about 3/8" thick over the 'buffleboard' siding to add some "R" value before installing the vinyl. Since my 2x4 walls are 16" OC, do I need to be concerned about losing wall strength by removing the masonite siding (which is close to 1/2" inch in thickness and in very BAD condition in spots. Going over the top is not an option since some of this siding is soft and possibly rotting. I see people all over that have done exactly what I'm doing and have heard no negative comments thus far. Any thoughts from anyone? (I guess I'm wondering if adding a thin sheeting like 1/4" plywood FIRST would stiffen the wall up to what it was when the masonite siding was on or am I worrying needlessly about this? I can't go too thick by adding anything much, or my windows will be recessed in too far!)
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Old 04-30-11, 04:03 PM
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Welcome to the forums!

I think it might be ok although I think you are suppose to replace and use plywood at the corners...... but I'm just a painter, the carpenters should be along later
Old 04-30-11, 04:41 PM
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It's sometimes referred to as "buffalo" board. It's basically just a fiber sheathing. Some types were asphalt impregnated.

Adding fanfold will add basically no r-value to the home. Your fanfold would have to be air tight to add the advertised r-value which it is not. Fanfold is used when you are going over existing siding and it provides a flat surface. IMO it would be pointless to use it, your money would be better spent elsewhere. Hopefully the guys removing the old siding will be careful and not put holes in your fiberboard sheathing.

You can apply vinyl siding right over that sheathing, but you would be wise to add housewrap first. Vinyl siding allows water to get behind the siding around windows and doors, around the j-channels. This is normal, and when you have housewrap, it protects the sheathing or underlying siding from water damage and mold. You will obviously have to nail into the studs since you do not have plywood sheathing.

If you did want to add plywood sheathing, now would be the time to do it. Ideally, you'd remove and replace all the window and door trim so that the plywood (and housewrap) could go behind the trim. But this may be more than you bargained for. 1/4" osb would be the minimum you could use, and it would be sufficient to hold a roofing nail for your siding. Plywood in any thickness would be superior, but osb is the least expensive option. 7/16" osb would be my recommendation, as thicker sheets will lay flatter than thinner sheet goods.

If you don't already have plywood on the corners, then it's likely that you have steel bracing (or 1x4 let into the studs) acting as bracing for your corners.
Old 05-01-11, 11:42 PM
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Thanks for the info so far. Another suggestion I had gotten was to use styrofoam sheeting instead and in either choice (that or fanfold) they had planned on using a special tape to seal everything up. Of course my other concern would be that I would NOT want any moisture problems occurring so it sounds like house wrap is probably a must. I'm assuming house wrap is attached with staples? If that's the case maybe any additional foam underneath won't be possible anyway?? thanks.
Old 05-03-11, 03:26 AM
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We install about a 1000 sq.'s of siding in a year so when I make these suggestions I've been there done that.
Any insulation should be done on the inside not the outside. Adding fan fold or thicker foam will cost far more, throw off every window and door opening, you would have to use 3" long nails to attach the siding and trim.
If this was my job I would strongly suggest removing all that trash off of the side of the garage and go back over it with 7/16 OSB and house wrap. What you have on there now adds no shear streingth to the building, will not hold a nail. Unless these guys have X ray vision you can bet there not going to be able to nail into the studs to hold the siding on the wall. You may as well use thumb tacks.
That sheathing was suppost to be run at least 1" below the foundation. If your garage was just built on top of the slab and they did not run at least one row of block on top of that then your siding is going to be to close to the ground. Siding and sheathing should be no closer then 6" from the ground. If it's to low then the weed wacker is going to distroy the siding and water will be wicked up behind the wall. What we do if the sidings going to be run to low is add a strip of coil stock that's bent into an L shape that's 1/2 X 6" and attach it to the sheathing at the bottom of the wall, run the house wrap, then run 1 X 6 vinyl lumber, with a piece of Z moulding on top of that. then run the siding.
I would question anyones thinking when they suggested using fan fold for this job. I agree with the other posted on it's money down the drain.
We have had to remove over 50 sq. of Cellutex (simuler to what you have) after removing all the siding on a home and replace it with OSB before because all the siding was falling off or was bucked up. Once it came off we found out all the siding was cut wrong, it was nailed to tight, none of it was nailed in the center of the nailing slots, there was missing insulation, live wires going no where behind the walls, vent thimble through the wall for the gas fireplace was intalled up side down (it was marked in big letters "UP") and in direct contact with the Cellotex which in big letters says Flamable and it had caught fire. ALl the widows were framed to big so only 1/2 the head of the roofing nail was holding in the windows, none had been nailed in the nailing slot. None of the windows or doors had window tape. Header over garage was an LVL that had been marked with arrows and the words "UP" every ft. and it was upside down.

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