Deck Vents

[Tonyg 14]

I am working on an estimate for one of my customers. They had a deck built in May by a contractor that likes to completely enclose the deck with a skirt without adding ventilation. This will be the second deck I've done that they have built that is like this. (They also applied a clear sealer that was supposed to be the 'best' sealant) In this case, the yard, with the amount of rain we have had this year, is completely saturated and it is causing obvious moisture issues with the deck.

Anyway, I am looking for ways to address the moisture on this deck and I am looking for a supplier of vents that could be used for decks. The deck is 30-36 inches high so would applying a vapor barrier and sand be something that would work with a deck?

Anybody installed vents likes this or applied the sand/vapor barrier?

[plainpainter 217]

Just Creto DPS the cr@p out of it.

[Tonyg 14]

Just Creto DPS the cr@p out of it.

I don't think this would be a solution. Applying the Creto would 'permanently' seal the top thereby trapping the moisture from leaving at all. I think vents are what is needed but not sure if that will be enough. Also curious about the sand.

[Adrian 155]

I have drilled pilot holes in skirts before for ventilation.

Almost completely unnoticed, it allows some air flow.

[plainpainter 217]

I don't think this would be a solution. Applying the Creto would 'permanently' seal the top thereby trapping the moisture from leaving at all. I think vents are what is needed but not sure if that will be enough. Also curious about the sand.

It doesn't seal the top, it seals deep inside - it would prevent the wood from taking moisture from below in the first place. It's not a surface treatment, I have used a similar product, you can apply coat after coat after coat on new pressure treated - and it sucks it all up.

[Celeste 341]

We add vents then maintain the deck as usual. It's a nice upsell considering the range of choices out there. If the homeowner has concerns about critters getting under the deck, we will usually install wiring behind any decorative type vents to prevent them from squeezing through.

[big mike 14]

As much as people hate to deal with lattice, its a good option on low decks. You are correct that the deck needs airflow, but just adding a vent or drilling holes isn't going to have the effect you're looking for. The moisture needs to air out quickly for it to be effective, otherwise rot will happen. Let the homeowner decide if its more important for the solid skirt, or replacing deck boards in 5 years.

[Celeste 341]

As far as lattice goes, we have talked more homeowners into letting us replace their existing wooden toothpicks with vinyl - after a full explanation of maintenance & future costs, they switch 98% of the time.

[big mike 14]

Good point Celeste. I really don't mind lattice, and i'd rather clean and stain it than replace floor boards. Vinyl lattice is a good option.

Tony, point out the moisture and mildew growth at the base of those skirt boards. They act like a wick and pull moisture from the ground. I'd give them another two - three years before they need replacement. So, it would be an easy up-sell for you, if you offered them lattice.

[Timo 25]

I think vents are what is needed but not sure if that will be enough. Also curious about the sand.

Tony,

If you do go with a moisture retarder, use small landscaping stones as ballast. They will dry out much faster than sand.

Sand stays too wet for too long.

[Celeste 341]

Good point Celeste. I really don't mind lattice, and i'd rather clean and stain it than replace floor boards. Vinyl lattice is a good option.

Tony, point out the moisture and mildew growth at the base of those skirt boards. They act like a wick and pull moisture from the ground. I'd give them another two - three years before they need replacement. So, it would be an easy up-sell for you, if you offered them lattice.

Mike - if you actually do the math, replacement costs less on both sides - we would MUCH prefer to tear out & replace than strip that aggravating, chem-wasting wood lattice.

[big mike 14]

Mike - if you actually do the math, replacement costs less on both sides

Maybe...... Here's my view; to replace lattice you need to go buy it, bring tools to remove the old and dispose of it, then install new lattice, and stain it (if it's wood). It may be cheaper, but time-wise, it takes MUCH longer.

That's a lot of extra steps and time when I could just downstream a little more stripper, rinse a bit longer, apply a little more OX, then spray some extra stain. The only time I even offer to replace is if the lattice is completely shot. Otherwise, it's just part of the total square footage.

(this pertains to deck skirting only)

To each their own.....:)

[Celeste 341]

I'm not talking about replacing wood with wood - I'm talking about selling vinyl replacement. Tear down is silly easy if the wood is already old - generally plenty is missing or rotten. We restore by the square foot - a 4X8 sheet of vinyl lattice, even in the cedar tone, is no more costly in labor & materials than restoration. Then, next year, little housewash and poof, it's clean - still charging but less for them and no hassle for us. It leaves a great look and savings to the homeowner, which they remember!

[Tonyg 14]

Here was an idea from Professional Deck Builder: Home. I wonder how it would look to pop the boards off and reinstall with 1/2-3/4 gaps? From the pictures it doesn't look like the top of the boards are accessible though.

"Airflow Below

It’s important to create opportunities for airflow beneath

low-level decks. If the design calls for skirting, enclose the

area below with open lattice, or use vertical boards with at

least 3⁄4-inch gaps between them."

I don't think the homeowner will want to scrap the sides for lattice but I don't think small vents will be enough flow. I think I will need to swing by and see what they are up for - vents, lattice, or a little creative carpentry. Even though the verticals are cedar, I don't think they will last long as it is with water wicking up the grain.

Outside of soffit or floor vents, has anyone used anything other type that may be designed more for decking?

Dan, there is no way any sealant is going to penetrate through a 2x4 deck board to keep it from "taking moisture from below". Coat one side of a sponge with plastic and the other side will most definitely continue to absorb moisture. I would think under normal circumstances the pressure treated wood preservative would do fine - under 'normal' circumstances. I could see 1/2-3/4 inch penetration on older wood but the only way to get that kind of protection on new wood would be to dip it.

[Celeste 341]

We've installed fancy wrought iron looking things - I'll try to find pictures. They look really nice.

[John Orr 206]

Tony, thermostatically controlled vents will work. Cut the opening and there is a bezel that will cover the edges. Batchelder & Collins in Norfolk sells the good ones - "Temp Vent" brand. They come in several colors - brown black and white as I recall.

As far a plastic/sand, I would skip the plastic on the ground, as this will allow water to sit on top. Plastic with holes punched-in (a screwdriver works well) would work, though if water can drip between the boards, the sand/plastic needs to be sloped away from the house.

The biggest problem with this (and most) decks is that they cut-off airflow in the crawlspace of the house - which can lead to many nasty problems - so curing the moisture issue with the deck will save the homeowner thousands of dollars down the road.

P.S. In another life, I was a manager for Terminix in Virginia Beach and have crawled MANY houses that were suffering due to lack of airflow caused by decks.

[acegot 14]

Tony, A good alternative that I have done for air flow, to get enough volumne to really do any good is install Gable vents, they look good, stylish with lots of styles. Available in natural wood also. Here is a link for a visual. Hope this helps. Classie Louvers: Louver Vents, Gable Vents, Custom Louvers

[Beth n Rod 1,279]

There's flimsy cheap lattice, and there is expensive, thick, durable lattice that is very nice. We prefer that, and also around here where everyone has a homeowners association, white vinyl lattice is not always an option.....

Beth :cup: :cup:

[Beth n Rod 1,279]

Tony,

None of what has been proposed is going to help with air flow as wind blows and creates vortexes. Swirling and turning. The deck is built into a "L" corner of a house creating a null zone. The wind will not be able to reach more than a couple of feet under the deck effectively.

--->This is the best way to solve the moisture issues: keep it from remaining under the deck.

To do this, you must remove all the deck floor boards, create a substructure to support a sill drain system made of corrugated fiberglass that drains to one side away from the house and then is diverted out from under the deck to a french drain 10'-12' from the deck to discharge.

Sealers on the wood and vents in the skirt are only expensive and ineffective little bandages on a severe issue with moisture retention.

I understand that this is a more expensive option but it it the correct option. The water must be kept from collecting under the deck and contributing to the rot and decay of the skirt and the dynamic flux of the deck itself caused by excessive moisture content followed by extended drying periods where any topical sealers will fail everytime.

Rod!~

Edited December 16, 2009 by Beth n Rod

[plainpainter 217]

Cretowood....end of story, nothing lasts forever anyways....

[plainpainter 217]

Here is something I have done for homeowners in the past - dig a hole underneath that deck, a drain basin so to speak, strategically placed where most water will drain into. If you have to cover up the rest of the area with that fish pond membrane material so all the water that gets underneath there gets funnelled into the drain basin. This basin will be filled with crushed stone and at the bottom run a pvc pipe that runs out to the backyard. You'll have to dig a trench the whole way as it will be about 2-3 feet underground and hopefully you have a nice slope where this thing will eventually re-emerge and let the water drain out. Or you could bury a drain basket into the ground - lots more digging - where this could drain into. It's a lot of work - but it will work great, and any remaining moisture will easily breathe out the gaps between the boards.

[RPetry 564]

I am working on an estimate for one of my customers. They had a deck built in May by a contractor that likes to completely enclose the deck with a skirt without adding ventilation. This will be the second deck I've done that they have built that is like this. (They also applied a clear sealer that was supposed to be the 'best' sealant) In this case, the yard, with the amount of rain we have had this year, is completely saturated and it is causing obvious moisture issues with the deck. ...

Tony,

If the ground below the deck footprint was properly prepared by the deck builder, it should be well drained. From your first picture, it appears that the PT deck boards were not gapped sufficiently, and the wood has swelled a bit. If the deck surface does not drain, your customer has a problem. But it is a design/construction problem that the builder should address.

We've worked on similar skirted decks in the past (see pics), without running into moisture retention issues. These decks dry out fine after preparation, and hold stain for the normal length of time. The only problem is the use of T&G cedar for the vertical fascia.

Over time, cedar will rot if it constantly stays wet. In the case of ground contact, it will slowly deteriorate from the ground up, but the process is slow and can take many years.

[acegot 14]

On the high dollar correct side of the issue, like Rod mentioned, herreis a system that drains the deck.( There are other patented systems too.) DEK Drain keeps the area under your deck DRY!. Double the use of your deck

[cleanhoods 43]

One thing how much does the customer want to spend.You can replace the skirt boards with those (i dont know the name) plastic type of decking boards and make sure there is a gap in between the boards for air flow 1/2 inch should be plenty. how long ago was the skirt put up cause treaded with time will gap and if it had the time you can remove all those skirt boards(the cheeper way) and have gaps inbetween the boards about a 1/2 inch so the deck can breath.

Marko

[MudDuck 20]

What about shadow boxing the skirt switching every other board (or some in a pattern) to the inside. Staple a critter net around the inside. Wont stop the ground wicking but when time to replace pour a small crete base footer that can be covered up with a little pebble rock for the boards to sit on. Shouldn't be too labor intensive to dig out. Without going back and looking at the pic can you saw in, install a nice vent on each side at the brick wall then knock out the front of the under steps (top board) and put a front vent with a step light there. Just an idea off the top of my head. I doubt the HO is going to go to the expense of doing a major re structure to do it right so your stuck with a "fix". Just have to figure out the most practical one.

[Tonyg 14]

What about shadow boxing the skirt switching every other board (or some in a pattern) to the inside. Staple a critter net around the inside. Wont stop the ground wicking but when time to replace pour a small crete base footer that can be covered up with a little pebble rock for the boards to sit on. Shouldn't be too labor intensive to dig out. Without going back and looking at the pic can you saw in, install a nice vent on each side at the brick wall then knock out the front of the under steps (top board) and put a front vent with a step light there. Just an idea off the top of my head. I doubt the HO is going to go to the expense of doing a major re structure to do it right so your stuck with a "fix". Just have to figure out the most practical one.

The HO is weighing options. This deck is less than a year old and I am pretty sure they will do what is needed. I have done a few jobs for them before so I am expecting they will do something in the spring so I will post an update to what they decide. They may even go back with the builder as they are not too happy that 'their' design has given them an expensive ugly deck after just a few months. Their biggest concern is doing something that is not sufficient to prevent the moisture or altering the aesthetics of the deck too much. I thought about something like shadow boxing but that would not create enough airflow and looked at foundation vents but it would not be practical. My suggestion was to either cut and frame out 1x2' square openings with cedar 1x4's and lattice or replace the cedar skirt they have now with lattice. It's winter and a good time to think about the options later in warmer weather.

Edited January 29, 2010 by Tonyg