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Do you build slope into your porches?

Posted by kate1234 (My Page) on
Fri, Jul 18, 08 at 7:17

Traditional instructions for building porches say to include a slope of 1/4" per foot away from the house to promote water drainage. Do you do this? My contractor is reluctant to do this, saying that a room that is not level will feel "off."


Follow-Up Postings:

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RE: Do you build slope into your porches?

Slope it if you are using T&G for sure. A regular deck with spaces between the boards can be constructed level.


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It Depends...

My wife and I had a covered front porch added to our house 3 years ago. Our porch flooring/decking is not sloped and it is tongue & groove (T&G). However, our material is 100% recycled plastic (it is the top-of-the line building material of our contractor - and this contractor has used it for over 20 years now). In addition, the front of our house where the porch attaches to the house is brick. So, while I believe the advice to slope your porch is good advice, I think it depends on site-specifc factors as well as all your building material, which you did not provide. For example, our porch posts and railings are vinyl, with an aluminum inside for structural support. If we would have used wood, then sloping the porch would be an issue, since you don't want standing water around the base of wood porch posts or newel posts.

I'm sure some of the contractors who regularly post here can offer additional insight on this issue.


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RE: Do you build slope into your porches?

I am intersted in a Contractor who has used solid re plastic for 20 years hmmmmmmmm very intersted...in fact very very intersted. mrdeck.com has several projects placed in that time period using solid plastic material but it is defentley not recycled .

In the very old days of wrap around covered porches a lot of slope was installed for some unknown reason mabey to prevent rot/decay..anyway whatever they did it seemed to work some of those places lasted 80 years or so. Of course you have to define faliure.

The 1/4'' per ft is standared with concreet far as slope away from the house goes but its not needed for a covered porch. With T&G material or face fastened decking I frame them leval. With the correct mill on the T&G decking and the right install no fall is needed. J


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RE: Do you build slope into your porches?

John, what do you mean "with the correct mill on the T&G decking and the right install." I'd love to know what to look out for in the choice of T&G (right now I'm leaning toward ipe but haven't ruled out Azek Porch) and what to tell my GC your advice is on installing it correctly. The boards will be perpendicular to the house. The house is faced with brick veneer, the frame of the porch will be pressure-treated lumber over piers. The porch will be 40" off the ground.

I expect some rain to come in on the edges, particularly when the storm is from the south as it does sometimes. The gable end which faces south really shouldn't have a roof overhang as none of the rest of the gables on my house do. The two sides will have an overhang so will get some protection.


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RE: Do you build slope into your porches?

O Man I was hoping that jdm guy was going to chime in again with the 20 year re cycle solid plastic thing,pretty sure thats total bogas.

Kate, I get my T&G ipe from George at EastTeak we have worked out a mill so the G is 1/8'' further in, the top edges are bevled and its not klin dried.

Most of the old porches ran the decking at a 90 degree from the house so your good if the old look is what your going for, although it really dosent matter what way the decking is running it will drain the same>> thru the gaps<<

Draining thru the gaps brings us to the ......drum roll.... Right Install!!!! acording to John>>> with the right mill install the T&G ipe with construstion adhesive on the joists,cut a 1/2'' slot in the T every 3' or so done corectley it wont show, do not jam the decking up with a vengance use a snug fit, run a SS screw thru the T with a slight pre drill using a 1/8'' drill bit( thru the ipe not into the pt joists) SNUG the G into the T this will allow hmmm an 1/8'' or so of gap. T&G ipe decking drains the same way as any other deckin thru the gap.

Of course this all depends on your frame having the right foundation, being Very secure, and no over spans.
No decks out with Azex cant help you there. J


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RE: Do you build slope into your porches?

Thanks John. If water can get out through the slots, can't bugs get in? I live in a very nasty bug area and I must be sweet-smelling because they bite me every chance they get.


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RE: Do you build slope into your porches?

Its the same gap T&G or face fastened.

Do not treat outside decking like an inside floor. J.


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RE: Do you build slope into your porches?

I use 5/4 x 4 T&G Mahogany flooring at 90 degrees sloped standard, whether open railing or screen-in.

The PorchGuy

Here is a link that might be useful: My Album


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RE: Do you build slope into your porches?

I am having a screened porch built,, using Azec porch floor, which is narrower than Azec decking and is tongue and groove. My understanding is azec porch should be laid on a slight decline of 1/4" to allow for drainage. My husband and I notice the floor did not appear to have this decline so he asked the contractor who said if it is on a deline, there will be an opening at the end of the screened porch to allow for drainage and will be a potential problem with bugs entering. Is this true? He claims he has an azec porch and has not had a problem with drainage. If the problem is an opening for drainage, couldn't a screen be put in place where the drainage holes are? I am concerned about rains, snow and drainage issues. Since this floor is tongue and groove, is there any way or room for water to drain? This is a second home so the house is unoccupied much of the year and I certainly would not want drainage issues and, possibly, compromise he integrity if the azec composite.
This is a big project and is quite expensive, so I would rather be proactive now rather than reactive later. I know very little about a screened porch construction, but I did some reading prior to making my decision on the azec porch vs, the azec decking. Maybe the recommendation for the 1/4" inch decline is for a porch that is not screened?? I might add this is in an area that has humid hot summers and cold winters with occasional snow and ice..

Please help.... I will be talking to him as early as tomorrow or Tuesday. I certainly do not want to put him on the defensive, but I need to know if this is standard practice. He does nice work and I am not in the trade, but at the same time, this is contrary to what I have read. Maybe we should go with the azec decking and save $2575, but I really like the look of the porch floor since it is a screened porch and not a deck. I also like the fact there are no visible nails on the floor.

Thank you, all, for your expertise and input!


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