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Update: Decisions made about porch and crawlspace. Thanks!!!

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Update: Decisions made about porch and crawlspace. Thanks!!!

Postby Abuela » Fri Jun 25, 2010 6:58 pm

Please see revised version of question here:
viewtopic.php?f=2&t=23844&p=207226#p207226


I need some help thinking outside the box with regard to options for my front porch.

Our foundation goes around the outside of the porch. The unfortunate result of this is that with any rainfall, water goes through the porch floor and into our crawlspace. We've determined that the beams under the porch are in trouble - not enough that they need to be completely replaced, but enough that the main corner beam needs some serious sistering and support, and the others are moving towards being damaged (in a way that they're not seeing in the beams under the main part of the house) and should be monitored. We also have a pretty significant amount of mold overall down in our crawlspace.

We are working with contractors to get bids for cleaning up the mold, and insulating and sealing the crawlspace in a way that will help prevent further mold. We appear to have two options.

Option 1: Build a wall to separate the part of the crawlspace that is under the porch from the part that's under the house so that we can properly seal off the part under the house. We would still need to keep a close eye on the beam under the porch, since this wouldn't at all address the water coming through the porch boards. This would allow us to keep the current porch floor or replace it with a regular wood porch floor.

Option 2: Put a flooring down on the porch that will not allow the water through. One contractor recommended something that doesn't sound like it' would look at all authentic for our house (don't remember the name). If there were a way that I could put something down that looked more authentic than this was described to me, I'd actually lean towards this because of the existing damage to the beams, and that the floor that's down there now is already questionable (several damaged/soft spot, needs to be repainted but I'm already concerned about how well it will repaint considering the damage).

I feel like I'm missing some essential pieces of information, like something I'm not considering or a product that would work well for this.

Suggestions and questions that would help me think this through are much appreciated.
Last edited by Abuela on Wed Jul 07, 2010 6:52 pm, edited 4 times in total.
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Re: Problems with water under porch - what are my options?

Postby S Melissa » Fri Jun 25, 2010 9:33 pm

Well, the first thing I thought of is ventilation. Unless you pour a concrete porch floor, any other floor will have some porosity - and rain/snow will seep thru. Without ventillation, it becomes a stinky moldy mess. I'm not certain, but I think you have a block foundation? If so, it would be easy to take out a block on each of the three sides of the porch and put in a vent (should be there anyway). They even have some that have little fans or something on them to move the air around a bit. If you block up the space between t he bassement and the porch crawl - make sure you vent it. Otherwise, any remedy you choose at this point will be temporary without keeping it dry.
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Re: Problems with water under porch - what are my options?

Postby Abuela » Fri Jun 25, 2010 10:48 pm

RE: Ventilation -- See, that's where I'm getting a lot of conflicting info, but my research is significantly tipping towards the opposite perspective, that

Constructing vented crawl spaces is a bad idea... Venting a crawl space with exterior, humid air during the summer months leads to the wetting of crawl space assemblies, rather than drying, since crawl space surfaces will be cooler than the outside air.


(from the Energy Efficient Builders Association Builder's Guide/Cold Climates as quoted in a related article.)

and, from a research article on the US Forest Service research site:

Crawl-space vents can, in fact, be counterproductive. Samuelson (1994) stated that introducing outside air into a cool crawl space during summer, when temperatures are most conducive to mold and decay actually raises crawlspace relative humidity. This practice can easily produce relative humidities of 85-95%, even in a crawl space with dry soil or a soil cover.


When I add in that I now have two evaluations from highly recommended/experienced contractors who both recommended the same basic solution (seal, not vent) I'm likely to go that direction.

If you have articles/information that would help me understand the opposite perspective, I absolutely want to read them!

But whether I vent or seal the crawlspace, I still must address the issue of water getting into the porch portion of the crawl space from the porch floor, and the resulting condition of the beams there...
"Finished" is all a state of mind. ~Angolito

People will forget what you said, people will forget what you did, but people will never forget how you made them feel.” -Maya Angelou

My house journal: http://retrovation.blogspot.com/
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Re: Problems with water under porch - what are my options?

Postby Nancy W » Sat Jun 26, 2010 12:46 am

I am not sure that the Mid-Atlantic area is really considered "cold climate". Remember we rarely get very much snow and usually when we do get it, it is gone the next day.

It seems very unusual to have the crawl space of the house extend under the porch. Most porches are built on piers and have LOTS of ventilation. I think I would be inclined to add the foundation wall under the exterior wall of the house at the porch and then open significant areas of the foundation under the porch.
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Re: Problems with water under porch - what are my options?

Postby Abuela » Sat Jun 26, 2010 12:52 am

Nancy W wrote:I am not sure that the Mid-Atlantic area is really considered "cold climate". Remember we rarely get very much snow and usually when we do get it, it is gone the next day.

I agree that we wouldn't really be considered cold, but what they wrote seems to me to be just as applicable (if not even more applicable) to our stifling summer humidity.

Nancy W wrote:It seems very unusual to have the crawl space of the house extend under the porch. Most porches are built on piers and have LOTS of ventilation.

Yup, which is probably why I'm finding so very little to go on.

I think I would be inclined to add the foundation wall under the exterior wall of the house at the porch and then open significant areas of the foundation under the porch.

We have a block foundation, and the blocks go up to hold up the porch columns. I honestly can't fathom how we'd be able to open it up at all.

I don't have a recent pic (this is actually from before we even bought it) but if you can mentally remove the ivy, you'll see here what I mean:

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"Finished" is all a state of mind. ~Angolito

People will forget what you said, people will forget what you did, but people will never forget how you made them feel.” -Maya Angelou

My house journal: http://retrovation.blogspot.com/
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Re: Problems with water under porch - what are my options?

Postby matchbookhouse » Sat Jun 26, 2010 10:28 am

Abuela, re: venting or sealing the crawlspace. My house (1927 bungalow-type) in coastal VA has a very small crawlspace, no more than 24 in. high. The water table here, since I'm so close to the Potomac River, is pretty much right at ground level. Plus, whenever there's a prolonged rain, the whole yard floods (another issue). The typical solution to crawlspace dampness here is to have vents or openings that are open in summer and closed up in the winter. However, I did a lot of research on the subject of crawlspace dampness (and mine was previously a real swamp that you couldn't have tasered me to crawl into, LOL), and I agreed with the research studies. Also, my house has a front porch (which was enclosed about 60 years ago), with a concrete block foundation that goes around the whole perimeter of the house.

The solution was to remove all the old vapor barrier in the crawlspace, grade the earth, and install a special heavy duty vapor barrier that was sealed to the interior of the sill plate, as well as all of the supporting piers. The barrier covers all of the closed-off old vents as well. Then a dehumidifier was installed in the crawlspace with an exit pipe that goes about 6 ft. outside the house. This worked well for the drier periods, but a prolonged spell of wet weather revealed that just the dehumidifier was insufficient to handle the extreme excess of rising ground water. The final fix was to install a sump pump. The dehumidifier empties into the sump pump, which empties it outside, and also has a battery backup AND is on the whole-house generator, so even if power goes out during a big storm or (like 2003) a hurricane, the crawlspace moisture is always being removed. You can set the dryness level on the dehumidifier, and it runs on-and-off as needed.
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Re: Problems with water under porch - what are my options?

Postby Abuela » Sat Jun 26, 2010 11:03 am

MBH, that is basically the solution that we are pursuing. Same issue here -- no surface water problems, just very high humidity area and very high water table.

Which brings me to the issue with the porch: We can't dehumidify in the crawl space if there are openings for rain to get down there. And I just don't have a flipping clue as to how to seal that off, or at least seal it off well enough that we can manage what does get through.
"Finished" is all a state of mind. ~Angolito

People will forget what you said, people will forget what you did, but people will never forget how you made them feel.” -Maya Angelou

My house journal: http://retrovation.blogspot.com/
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Re: Problems with water under porch - what are my options?

Postby Raine » Sat Jun 26, 2010 1:31 pm

Make sure your gutters are working. I would DIY mold clean up until you know exactly your plan for your moisture problem. Use a dehumidifier. I used a garden sprayer with diluted bleach and sprayed my crawl walls. I also used an ozone machine.
Is the moisture problem due to only the porch floor? fixing that, you would not have to build a wall. " thinking out of the box"-- Porch shutters ? rolled awning ? Way out of box--- lifling porch floor and install a water containment/ shedding material ( metal roofing ?) spacer then put back floor. Of course it would have to slope away from house. Or build that wall and knock out the porch walls open to air like other porches. Good Luck
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Re: Problems with water under porch - what are my options?

Postby YinzerMama » Sat Jun 26, 2010 5:01 pm

We don't have a front porch, we have a front sun room ... it's enclosed and has always been that way. The foundation of the house goes all the way around so the sun room has accessable cellar under it... it's not a crawl space since you can stand in it, it's a storage room. We call it the asbestos room or the scary because there are asbestos pipes in there. We don't use it for much, just to store some stuff. And very limited stuff as I am afraid of whatever going in there stinking...

I can't stand how it smells in there. I have crazy sensitive sense of smell. My husband says "I don't know, it smells musty, I don't get the big deal" but I go in there and I come out gagging. So we keep the door shut and I don't go in there. '

It has 2 windows and come to think of it they were open last summer and it did not smell as bad. So I don't know. maybe ventiliation is key. I put 4 od those damp rid buckets in there and it didn't make a difference.

I've been told the only way to beat this is to excavate and seal the outside with tar. Since this isn't a porch, for us, it's not water coming through the floor... it's moisture through the bricks.

I have no idea what the rest of the basement doesn't smell this bad. There's another little jut out in back - a back sun room - and POs made that area a bathroom with a sink and shower and toilet. It's a little damp and the towels go funky a little faster than I'd like in the summer but it doesn't smell like the front room.

Anyway I have no advice. But commesiration. My solution is just not to go in there!!!
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Re: Problems with water under porch - what are my options?

Postby Raine » Sat Jun 26, 2010 9:23 pm

I just remembered viewing a house that when in the dug out hole in the crawl ( wanna be basement) I could see under the porch. They had an obvious moisture problem and carpenter ants. I can now feel what you have going on ( although I havent seen your situation) I would build that wall and cut out holes in the porch walls for vent. Holes big enough for access to inspect structure and cover with critter proof removeable panels.
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