How to Redo Porch With Solid Rock Foundation?
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dtotzz



Joined: 04 Mar 2020
Posts: 9
Location: Newmarket, NH

PostPosted: Mon Mar 08, 2021 11:58 am    Post subject: How to Redo Porch With Solid Rock Foundation? Reply with quote

When I purchased my 1900 New England home the original front porch posts were replaced with ugly square boxes. I've ordered custom-turned posts to match the existing half posts which thankfully have been preserved.

Replacing the posts seems like a good time to also replace the ugly 1x5 spruce decking (laid parallel to the house) with a traditional CVG douglas fir tongue and groove porch floor. However, the porch is very low to the ground and has a solid 7" concrete foundation going around the perimeter of the porch. The prior owner smashed the decorative stone wall in order to make room for a rim board.

I'm concerned about having a solid porch foundation and the effects that will have on the porch floor. The porch is about 8' wide and 11' long.


I'm concerned that a solid porch floor laid over a solid foundation will trap moisture, causing premature failure of my porch floor. Currently, this space is vented by ugly 1/4" gaps between the porch floor.


What are the best ways to secure the porch floor to the stone/concrete foundation? Or the joists to the foundation?



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johnleeke
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Joined: 20 Aug 2004
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Location: Portland, Maine, USA

PostPosted: Thu Mar 11, 2021 2:43 pm    Post subject: Reply with quote

Dan,
To start off, a series of questions:

Which of my books do you have?

Are you intending to keep the existing framing? That looks like pressure treated wood, can you confirm that?

Do you want to paint the new deck boards, or have a natural wood look?

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John

by hammer and hand great works do stand
by pen and thought best words are wrought


Last edited by johnleeke on Thu Mar 11, 2021 3:56 pm; edited 1 time in total
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dtotzz



Joined: 04 Mar 2020
Posts: 9
Location: Newmarket, NH

PostPosted: Thu Mar 11, 2021 2:53 pm    Post subject: Reply with quote

Thanks John!

I just have one book from you right now:
Practical Restoration Reports Compendium

The wood is pressure treated. I'd like to keep the existing framing but it might need to be removed/rotated 90 degrees so my floorboards can run perpendicular to the house. Alternatively, I could add blocking in between the existing joists.

I'm planning to paint the porch floor.
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johnleeke
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Joined: 20 Aug 2004
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Location: Portland, Maine, USA

PostPosted: Thu Mar 11, 2021 3:42 pm    Post subject: Reply with quote

Deck Boards:
When possible it is best to lay the boards perpendicular to the path of traffic, in this case, the same as the existing boards, which would work if you will be keeping the existing foundation and framing.

Foundation & Existing Framing:
Let's first consider keeping this system and see how far we get. This would be a significant saving of time and materials if it could be used as is.

Moisture Mitigation:
The porch deck will last longer the drier it is kept. Here are a few basic recommendations.
--Drainage: Add gutters at the eaves of the roof and conduct the water away from the porch with downspouts and ground leaders.
--Drainage: Regrade the soil around the porch so it slopes slightly away from the porch for at least 5 feet. Over to the right side of the porch it looks like there is a lot of erosion from water draining along the side of the house toward the porch. Is this the case? If so, does that water go along the porch too?
--Air Circulation: Under the porch deck it looks like there is some rubble and debris. When the deck boards come up, be sure to remove all that, and possibly dig out a few to several inches of soil to make a clear air space.
--Air Ventilation: The existing scheme of spaces between the deck boards provides at least a little air ventilation. Consider laying the new boards the same way, without tongue and groove, just square edged boards with a 3/16" gap.

Wood:

--Appearance: instead of planning on painting the deck boards, consider a "stain" that could even out the appearance of the wood and give it some color. The advantage over paint would be easier maintenance and allow the wood itself to give off more moisture than with paint. None of the current "stain products" are suitable, so you could mix up your own water repellant penetrating stain. This finish would require an easy re-treatment about every 5 years. (more details later if you need them)
--Preservative Treatment: Treat the new deck boards on the bottom side with a migrating borate preservative to prevent fungal decay. The exposed structural framing could get the same treatment. A specific product to consider is BoraCare. (more details later if you need them)

So, this scheme of keeping the existing foundation and framing, with the above details, might give you a deck with a life span of 20 to 30 years, if you keep up with that 5-year maintenance program.

Foundation & Framing (alternative)
Take out all the existing framing. Removed the stone foundation down to grade level at the sides of the porch. If the foundation at the front of the porch is adequate it could be left in place and used. This would provide the opportunity to have cross ventilation side to side under the deck. If the front of the foundation is inadequate, then it could be removed too. This would result in a clear area to put in 4 foundation piers, framing and deck in the more typical way. But, this approach would be much more costly than using the existing foundation and framing. This could give you a porch deck with an expected life of 40 to 60 years.

_________________
John

by hammer and hand great works do stand
by pen and thought best words are wrought
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dtotzz



Joined: 04 Mar 2020
Posts: 9
Location: Newmarket, NH

PostPosted: Thu Mar 11, 2021 5:10 pm    Post subject: Reply with quote

It amazes me how interconnected all of the systems of a house are...

There were no gutters on the house when we moved in and we were experiencing major water issues in the basement, so now there's a gutter on that side of the house and it drains next to the porch. There used to be a walkway there which is why the ground looks eroded. We're hiring a landscaper to lay granite steps leading up to the porch and they will address the downspout and grading issues.

The original molding is missing from the eaves of the porch roof, so replacing it with a gutter instead of molding could be a neat way to solve two problems at once!


The prior owner wasn't a big fan of cleaning up his workspace or making trips to the dump so there's a lot of old stonewall/walkway/asphalt under the porch floor, I'm planning to clear that all out.


Boracare was already on my radar after reading your praises of it here and in your book. I'll apply it to the joists as well as the floorboards.


I'll redesign my sketchup model with the gap you suggested, probably won't detract from what I was initially hoping for too much, and would be better than punching holes into the foundation.


Thanks for all of the advice!
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johnleeke
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PostPosted: Fri Mar 12, 2021 10:54 am    Post subject: Reply with quote

You are welcome. Keep us posted on your progress. Take care. Work safe.
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by hammer and hand great works do stand
by pen and thought best words are wrought
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