Skirting Vents?

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Greg
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Mon Jun 16, 2014 9:00 pm

I won't tell you have it backwards, but I will tell you that in warm weather you really can't have too much air flow under your home. You have to balance security against unwanted "Guests" getting in and fresh air flow. I used to have screened panels that I would install in warm weather, and replace them with insulated panels in the winter.

If I remember correctly you were dealing with some rotted wood issues, Moisture is always a major factor in wood rot. You want the area under your home as dry as possible since moisture will creep into your home any way it can.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."


ponch37300
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Tue Jun 17, 2014 11:14 am

thatswhoiam wrote:in hot/ humid climates, vented mh crawlspaces are not recommended.

somebody please tell me i don't have that backwards. i've got about 1/4 of the vents closed off
I would not close up the crawl space in hot and humid weather. You will have stale air just sitting down there creating moisture. In the article you linked to they show a crawl space that is completely closed off and sealed. But it is also conditioned, that is the key. The article shows the thermal break all around the "skirting", or concrete in their case, with insulation. And also a ground vapor barrier. Then they condition that area by pumping A/C in there. So basically the crawl space becomes part of your "living area". And if you live in the cold you will have to heat it during the winter.

The problem with that example and a MH is you can't really totally seal the crawl space and create a good thermal break at the skirting. MH move and shift and the skirting never really is "sealed" per say. You can get close but not close enough for me to condition that area with A/C. You would waste way to much energy conditioning it. And unless you condition it and have a good thermal break you will have condensation and moisture under there causing problems. That is why most just vent it, it's cheap and easy to do. Then those of us that live in the cold climates in the winter can seal the vents off if needed. I personally just leave the vents alone in the winter and as long as my underbelly and insulation is in good shape I don't have problems. The skirting, even with vents, keeps most of the wind out and some of the cold. Then the belly and insulation are the thermal break and keep the pipes and house warm.

Norm Frechette
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Tue Jun 17, 2014 1:01 pm

Image

I have a 2007 mobile home on a concrete slab and it has the type of vented skirting shown above and I have no problems at all with it

I live in Connecticut and it can get pretty damn cold in the winter and pretty damn hot and humid in the summer. no problems with the skirting

I have never put any kind of insulation on the vents.

ponch37300
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Tue Jun 17, 2014 6:56 pm

That's similar to what I have and it works great for me. It lets air flow in the summer so there isn't any moisture or condensation. In the winter I don't seal them either and as long as the belly material is in good shape I have no problems either. Around here this is the standard for skirting since we have cold winters and hot summers.

Annie410
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Sat Jun 21, 2014 8:01 pm

Thank you all for the feedback, weather permitting, the skirting will be done this week, then on to the painting, and hopefully I can get some photos up soon!


terrifromohio
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Fri Jul 11, 2014 10:16 am

Annie,

I have exactly the same type of vinyl skirting that Norm has in the above post. Previously had OSB board that rotted from the bottom up. So had new vinyl skirting installed last fall.
It is vented just like Norm`s. Had no problems this past winter even in minus 40 degree temps here in Ohio.

Terri

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Greg S
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Fri Jul 11, 2014 5:05 pm

In cold climates insulated skirting insures that the area under your home will not freeze and actually makes your floors feel warmer. Radiant heat is captured under the home rather than escaping through the skirting vents. This results in lower heating costs.
An individual must enforce his own meaning in life and rise above the perceived conformity of the masses. (Anton LaVey)

Annie410
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Fri Jul 11, 2014 7:20 pm

The job was finally done today, the rain has been holding us back, I opted for the vented, and will use the insulation board behind it this winter. Insulated would have been great, but it wasn't in the budget at this time, and I may be kicking myself for that compromise when winter rolls around.

terrifromohio
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Mon Jul 21, 2014 9:21 am

As long as your underbelly is good and insulated and sealed up you should not have any problems. I could not do the work my self so had to go with the cheapest option which was the vinyl skirting but the guys who installed it went through underneath the trailer and sealed up and insulated anything that needed it before they installed the new skirting.
Of course they charged me for it but I knew it was done right and as I said I had no problems.

Terri

Annie410
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Sat Aug 02, 2014 11:33 am

They did check the underbelly, terri, and everything was in great shape.

Thanks for the help everyone!

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thatswhoiam
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Wed Aug 06, 2014 8:00 pm

most of the weatherization programs now use the unvented skirting with the 6 mil liner on ground and the thick material covering the bottom of the mobile home (bottom board). also make sure there are no duct leaks. all those things together help prevent moisture from getting in the home. of course there is no way to close the home off to moisture entry 100% , but 75% is a far cry better than just further letting it all in by way of vented skirting.

ponch37300
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Thu Aug 07, 2014 11:27 am

The subject of venting has to take a lot of different things into consideration, it's almost a science. Things like location, temperature, humidity, etc all have to be taken into account to make an accurate decision. Also if you live in the areas a lot of us do where there is a hot season and a cold season you have to take both situations into account. So there is no one solution fits all for this topic. There is also a broad range of theories on the subject of insulation and venting, not just in MH but also in traditional homes. So the best we as home owners can do is to do our research and form our own opinion on what will work best for us.

For cold climates no vents and insulated is going to keep most of the cold out and keep what heat is under the trailer under there. I don't think there is too much to debate on this part.

The debate comes when dealing with the heat and humidity and stale air and moisture. Our crawl spaces are not conditioned, unless your underbelly has been compromised the space under the trailer has a thermal break from the conditioned living areas. If you don't have any vents and it is hot outside and humid then you will have stale air that is just sitting under your trailer and will most likely cause moisture issues. Think of it this way, if it is 90 degrees out and humid and you close up all your windows and don't have AC your house is "unvented" and will heat up and become very uncomfortable. Now, in the same situation if you open your windows you are "venting" your house and at least some of the trapped hot air can get out and a breeze can cool your house. This same applies to the space under the MH, even if it's insulated.

I've done a lot of roofing on traditional homes and am certified by certainteed. One of the things they teach you is proper venting on the roof system is needed. While this isn't the exact same as the space under our MH a lot of the same principals apply. In a house with an attic you want the attic to be vented, in the hot and the cold. The attic is unconditioned space, just like the space under our MHs. When a person finishes off an attic or wants to insulate the rafters they MUST leave a gap under the roof sheathing that is vented, otherwise you will have a lot of issues with moisture. We do this by using some foam pieces that get stapled to the bottom of the roof sheathing and leave about an inch gap for air to travel from the soffit to the ridge and both have to be vented. I have seen first hand the damage that happens when a person puts insulation tight up against the roof sheathing and not vent it at all. I know an attic is a little different then under a MH but they are both "unconditioned" spaces and can benefit from venting.

I have not seen one article by a creditable source that says venting under a MH is a bad thing, especially in hot and humid conditions. The links posted above were for a crawl space for a traditional home and most of that can't be applied to the space under our MHs. Also, moisture doesn't get in through the venting. Venting can actually be one of the best deterents to moisture.

Steve S.
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Location: Maine

Fri Aug 08, 2014 6:35 am

Very well stated Ponch...I know in cold moist climates the tendency would be to seal everything up and not allow for any air penetration, but during the summer months you can get all sorts of moisture-related problems in a trapped environment space. When my underbelly was sealed up with OSB panels I had puddles of water, rust forming on my steel beams, and black mold forming on the backside of the wood panels. Once I installed the breathable vinyl skirting, all those problems went away and it was a joy(almost) to venture underneath to check on things :wink: .

Norm Frechette
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Location: Norwich, CT

Sat Aug 09, 2014 7:46 am

my vents look like this. no problems whatsoever and i'm on a concrete slab. no insulated skirting either

my dads mobile home has the same vent on dirt and has no problems either

Image

both homes are in connecticut and believe me we do get our share of extreme hot and humid weather followed by cold in the winter

no frozen pipes in the winter and no humidity puddles in the summer

Annie410
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Sat Aug 09, 2014 8:31 pm

That's what I went with, Norm, and I'm moving to Central NY from VT. Hopefully here in NY permanently before long.

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