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bioman438 04-27-2013 12:52 PM

Porch flooring
 
Hey guys,

So I have a house in the northeast that was built in the 1920's. It has a covered 8' x 24' front porch. The porch is over a small room in my basement that I use as storage. The current porch is painted over tongue and groove. It is in need of replacement because the paint is peeling off and the boards are starting to rot. The porch leaks in a few place only when I get a heavy rain. I am planning on ripping off the old tongue and groove and replacing it with new douglas fir tongue and grove pretreated on all 6 sides with a good semi transparent deck stain. I would love to do a subfloor with roofing material underneath the doug fir, but my front door treshold is level with the current floor leaving me no room.

I understand that tongue and groove isn't meant to be waterproof, but I'm hoping that with the porch being covered, a good water shedding stain and being sloped away from my house it may keep my storage area dry. What do you think? Am I being naive? Is there something else I can do to help my cause (ie. caulking inbetween each board)? Any thoughts and advice is greatly appreciated.

Thanks,
Mike

jagans 04-27-2013 04:40 PM

Yes you are being Naive. I have never heard of an open porch that is over the basement. Porches on houses like this were usually built on piers, and the foundation ended at the exterior wall line of the house. Yours is unusual. I guess your best bet would be to cover the joists with tongue and groove plywood, then a peel and stick material like ice dams protection, then install 1 x PT sleepers parallel to the slope, and run your decking perpendicular to the sleepers. You may have to cut down and sister your current joists to gain some depth. You will need a base flashing against the house, and a drip edge outboard, and you want to slope this porch at least a 1/4 inch per foot. Envelope your sleepers to really have a good chance of making it water tight.

bioman438 04-27-2013 06:55 PM

1 Attachment(s)
Thanks for the quick response. After removing the old floor I'll have about 3/4" to work with. To cut down the old joist I would be removing a lot of material. I guess this is why you recommend sistering the joists?

Here are some pictures to give you a better idea of what I'm working with. Thanks again.

jagans 04-27-2013 07:59 PM

Nice House. Very unusual having the basement run under the porch like that. Yes that is what I was referring to with sistering joists. You may also wish to consider installing plywood, then EPDM, a drainage board and decorative interlocking pavers instead of wood. Basically builing an inverted plaza deck type system. Google IRMA, Inverted roof membrane assembly for some ideas.

framer52 04-27-2013 09:00 PM

You need to just install new covering. The problem is that the new T&G will be liess than 1" as opposed to the old real 5/4.

anyway, you could also use artificial wood but i wouldn't in this application. I trust the wood to seal better at the joints.

Your porch arrangement is certainly unusual, but not unheard of.:thumbsup:

user1007 04-27-2013 09:05 PM

I think I would use a solid exterior plywood decking material covered with something nice and other than t&g unless you really want that look. Some sort of membrane you can walk on in the color of your choice might work well. You can get it in different colors, textures and thicknesses (artificial tennis court material comes to mind but perhaps something with a bit more class for a porch). Or you could use something like large rubber tiles or something like that. Rubber is easy to lay, maintain and repair. It holds up to weather nicely. Again it comes in all kinds of shapes and patterns.

jagans 04-28-2013 09:31 AM

Google Duradek. This will do what you want, and will not raise the level of your deck.

bioman438 04-29-2013 04:38 PM

Thanks for the all the great info. I'm kind of committed to tongue and groove since I already had it ordered and delivered.

I think what I am going to do is rip the old 2x8 joist out and put in new 2x6's. this should drop the floor down low enough to do a subfloor. Currently the joists run parallels to the front of the house, but I'm going to change that so they run perpendicular leaving less than an 8' span. Any thoughts on what to put down on the plywood? Would felt paper work or should I do a rubber roof material?

JohnMargaret 11-05-2013 03:39 PM

Quote:

Originally Posted by jagans (Post 1168347)
Yes you are being Naive. I have never heard of an open porch that is over the basement. Porches on houses like this were usually built on piers, and the foundation ended at the exterior wall line of the house. Yours is unusual. I guess your best bet would be to cover the joists with tongue and groove plywood, then a peel and stick material like ice dams protection, then install 1 x PT sleepers parallel to the slope, and run your decking perpendicular to the sleepers. You may have to cut down and sister your current joists to gain some depth. You will need a base flashing against the house, and a drip edge outboard, and you want to slope this porch at least a 1/4 inch per foot. Envelope your sleepers to really have a good chance of making it water tight.

I have this same style porch (1920s house, open porch built over small storage room in basement as well as over the garage). I am having the same issue with porch rot.

JohnMargaret 11-05-2013 03:43 PM

Bioman438,

I am very curious what you ended up doing about your porch. I am currently dealing with the same issue with my porch. About to add a new membrane and sleeper boards under the new T&G fir that will go down. Curious what you did and how it worked out.

joecaption 11-05-2013 03:46 PM

You could have used composite T & G or kiln dried after treated fir T & G.
Ya I've yet to see any porch built over a basement not leak. Just a very bad idea to begin with.

JohnMargaret 11-05-2013 03:48 PM

Seems like it was common with in the 1920s.

joecaption 11-05-2013 05:44 PM

John it would me best if you added your own post. Way to confusing trying to keep the answers straight.

bioman438 11-08-2013 12:51 PM

John,

We ended up ripping the old flooring and framing completely off. The framing was made up of 2x8's running lengthwise parallel with the house with a beam in the center. (These were actual 2x8's and not nominal measurements.) We replaced them with 2x6's running perpendicular from the house. That gave me the 2 plus inches I needed to put down plywood with a rubber roof membrane. On top of this I did my 2x4 sleepers with vertical grain douglas fir tongue and groove flooring. I'm happy with the way it turned out and when I get home I'll try to get some pictures.


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