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T and G Exterior Porch Flooring

jameshartsallen's picture

Hi All, 

I live in an old 1860's house in Bucks County, PA. My back porch rotted out, and I was going to replace it. It was a T&G 1x4 material which was originally used, and I bought the same material (I think its Red Balau- or Phillipine Mahogany) to redo it. I am a little concerned because the porch is exterior, and is partially covered. Some parts of the porch will take some rain and sun. I am priming all the boards (front and bottom, as well as inside the grove and tongue) to try to lessen any moisture from getting into the boards. I was also going to pitch the boards away from the house somewhat so the rain sheds off of them. I planned on cleat nailing them with 2" SS L-shaped cleats. I wanted to install the boards as tight as possible (T&G) so that the floor is smooth and gaps are minimized.

The porch is roughly 8' by 18". It has a roof over 85% of it.  

My question is will the boards cup and buckle if I install them tightly? Will they expand and pop once the weather gets rainy and humid? 

I really appreciate any and all opinions/wisdom, thanks. 

James (post #214589, reply #1 of 10)

Here in NW Oh. we would be seeing fir flooring on porches or maybe whatever local was milled up.  I replaced a small uncovered entry stoop on an 1870 house.  It very well might have been original.  This and the frame below were old growth wood, nothing like what is available today.

As to your wood selection I have not used it.

but,

Some things in addition to sealing all side and cuts and sloping would be to make sure there is dry and free flowing air beneath the structure.  One side moist and one baked in the sun is sure to cup and split the flooring.

Acclimating the flooring to its surroundings is as important outdoors as in.  You want to bring the moisture content close to what it will be on that porch.  And always give it a place to move seasonally.

A "water table", drip edge or kerf is a good idea around the perimeter.  Rot and decay love end grain and for some reason water makes its way under the flooring and between it and the frame on the downhill ends.

A nailer and SS cleats have worked well for me.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


Thanks for the info, (post #214589, reply #3 of 10)

Thanks for the info, Calvin

The porch is built on a stone foundation (about 4' high), so I think there should be enough air movement beneath. In terms of the boards expanding seasonally, Im wondering how to accomodate so that they have space. I like the idea of acclimating them before install (couple of days to acclimate?) Should I put in gaps between the boards (1/4" or so?), or set them in tight? One side of the porch butts into a wall (which is covered by roof) and the other end of porch juts out in the yard (uncovered by roof). 

For the drip edge, do you just run a kerf on the underside of the end of the board? 

I appreciate your input, thanks man! 

J (post #214589, reply #10 of 10)

jameshartsallen wrote:

Thanks for the info, Calvin

The porch is built on a stone foundation (about 4' high), so I think there should be enough air movement beneath. In terms of the boards expanding seasonally, Im wondering how to accomodate so that they have space. I like the idea of acclimating them before install (couple of days to acclimate?) Should I put in gaps between the boards (1/4" or so?), or set them in tight? One side of the porch butts into a wall (which is covered by roof) and the other end of porch juts out in the yard (uncovered by roof). 

For the drip edge, do you just run a kerf on the underside of the end of the board? 

I appreciate your input, thanks man! 

You're welcome.

Is the crawl dry and is it vented?

I am not familiar with what exterior mahogany flooring would do in regards to moisture content swings.  I do think bringing in real dry lumber from a protected yard to use outside would require a bit more time to acclimate.  Stickered and laid out under the protected cover of the porch roof for whatever period of time is necessary to equalize it would be smart.  Don't lay it out on horses with visqueen over it.

The gap at the wall and a place for it to go on the end as mentioned.

Gap? no. Running the board with the pitch, yes.  Across the pitch, no.

I've removed a lot of bad shape 3/4 porch floor that had rot on the underside of the overhanging edge of porch.  Maybe from lack of good sealing over the years, maybe from the spring of the ends near the steps, even some, reason unknown.  But, where there's been long lasting install, no big overhang, maybe a horizontal pc under it and a time or two where they did make a water dropping kerf on the bottom side (which seemed a lot of work for the purpose).  Makes sense since it used to be on the underside of wood window stools.

Caulking the flooring to apron joint both between the two surfaces and the finished joint would be good.

At any rate, any caulk sealent I'd use would be urethane as in my experience it handles movement and keeps on sticking in most all applications.  Bich to work with, long to last.  Know it before you use it in visible locations or you might just throw it and the gun with your dark stained fingers, out in the field.....

Best of luck!

 

.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


If you can afford it, there (post #214589, reply #2 of 10)

If you can afford it, there are some great composite porch floor boards.  But at something like $15 a square foot, they're danged expensive.

Composites (post #214589, reply #4 of 10)

In retrospect I would have probably gone with composites. I already purchased the TG mahogany boards though, so Im stuck with them. I was trying to stay with materials that would have been historically accurate, but probably just made my life harder. 

Oh well, such is historic restoration/preservation! Its never easy, but its always fun. 

Porches decked in mahogany (post #214589, reply #5 of 10)

Porches decked in mahogany  are very common in the northeast. Sealing all six sides and using SS fasteners is definitely a “best practices” move and is more than a lot of people would do. Most of the mahogany porches I’ve seen are decked without any gaps between boards but you should leave a space at perimeter for expansion. 

Porches (post #214589, reply #6 of 10)

Thanks Steve, 

What kind of space should i leave at the perimeter? Or, how much expansion should I anticipate? 

expansion joints (post #214589, reply #7 of 10)

To answer your question: 3/8" expansion at walls. Anything greater is overkill. Install the boards snugly. Prime faces, edges AND field-cut ends. I'm glad you did NOT go composite. As others have noted, with the proper precautions and good maintenance your boards will last a long time. 

Mel Fros froscarpentry.com

Thanks for the input. Ill (post #214589, reply #8 of 10)

Thanks for the input. Ill keep that in mind. 

One other thing, the boards I have had a wax on the ends (sealer)- I was going to just leave it on, and not bother priming. Is that a bad idea? If so, can I just prime over the sealer? 

Thanks in advance 

That's a good question. I (post #214589, reply #9 of 10)

That's a good question. I always assumed the wax was not compatible with the paint or stain and cut it off to be safe. 3/8" at the permimeter should be fine but it really depends on what size your porch is. The lumberyard/rep will have better info on all of this.