Protecting the tops of deck joists - or not?
There appears to be a school of thought in deck building that it is worthwhile to protect the tops of joists by covering them with a waterproof barrier. That way any moisture can't sit on the top of the joists, soak in, and gradually cause rot or premature failure in pressure treated wood.
(Here's Matt Risinger's example of this).
However I've also read the viewpoint that while this practice may protect the joists it can also increase drying times for the deck boards. Assuming the decking is wood this seems like a significant risk.
I would imagine that the value of this is highly dependent on climate, the wetness of the site, solar exposure, etc. But I'm assuming the site is wet or else this wouldn't seem to matter one way or the other.
Also, though a cynical point of view is that this idea is driven by product company marketing strategy; but that itself doesn't mean it has no merit.
Is there yet any industry consensus on practices in this area? For example: building codes, studies being done as decks have aged, etc.? I'm open to global perspectives although I'm in the US myself.
deck
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
add a comment |
There appears to be a school of thought in deck building that it is worthwhile to protect the tops of joists by covering them with a waterproof barrier. That way any moisture can't sit on the top of the joists, soak in, and gradually cause rot or premature failure in pressure treated wood.
(Here's Matt Risinger's example of this).
However I've also read the viewpoint that while this practice may protect the joists it can also increase drying times for the deck boards. Assuming the decking is wood this seems like a significant risk.
I would imagine that the value of this is highly dependent on climate, the wetness of the site, solar exposure, etc. But I'm assuming the site is wet or else this wouldn't seem to matter one way or the other.
Also, though a cynical point of view is that this idea is driven by product company marketing strategy; but that itself doesn't mean it has no merit.
Is there yet any industry consensus on practices in this area? For example: building codes, studies being done as decks have aged, etc.? I'm open to global perspectives although I'm in the US myself.
deck
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
3
I can't answer the question as asked, but I can say, after demolishing, repairing, and restoring many aged decks, that the tops of the joists aren't exactly an Achilles heel. If the deck is old enough that the integrity of the fastening surface is degraded beyond utility, so are the joist ends, beam connections, posts, etc. At that point, since the decking is probably being replaced anyway, it's a fairly short step to a total rebuild. Whacking one proverbial mole doesn't yield much extended deck life.
– isherwood
5 hours ago
I'm with isherwood on this one - the tops of the joists are one of the last things that I would expect to fail on a deck. Even the decks I've worked on where the decking was completely rotted off the fasteners, the tops of the joists were almost always sound. Also, if you're using a composite decking, you'll find that most? of them have cups or groves milled into the bottom of them and don't really have a lot of direct contact area with the tops of the joists that would prevent them from drying out.
– Comintern
56 mins ago
add a comment |
There appears to be a school of thought in deck building that it is worthwhile to protect the tops of joists by covering them with a waterproof barrier. That way any moisture can't sit on the top of the joists, soak in, and gradually cause rot or premature failure in pressure treated wood.
(Here's Matt Risinger's example of this).
However I've also read the viewpoint that while this practice may protect the joists it can also increase drying times for the deck boards. Assuming the decking is wood this seems like a significant risk.
I would imagine that the value of this is highly dependent on climate, the wetness of the site, solar exposure, etc. But I'm assuming the site is wet or else this wouldn't seem to matter one way or the other.
Also, though a cynical point of view is that this idea is driven by product company marketing strategy; but that itself doesn't mean it has no merit.
Is there yet any industry consensus on practices in this area? For example: building codes, studies being done as decks have aged, etc.? I'm open to global perspectives although I'm in the US myself.
deck
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
There appears to be a school of thought in deck building that it is worthwhile to protect the tops of joists by covering them with a waterproof barrier. That way any moisture can't sit on the top of the joists, soak in, and gradually cause rot or premature failure in pressure treated wood.
(Here's Matt Risinger's example of this).
However I've also read the viewpoint that while this practice may protect the joists it can also increase drying times for the deck boards. Assuming the decking is wood this seems like a significant risk.
I would imagine that the value of this is highly dependent on climate, the wetness of the site, solar exposure, etc. But I'm assuming the site is wet or else this wouldn't seem to matter one way or the other.
Also, though a cynical point of view is that this idea is driven by product company marketing strategy; but that itself doesn't mean it has no merit.
Is there yet any industry consensus on practices in this area? For example: building codes, studies being done as decks have aged, etc.? I'm open to global perspectives although I'm in the US myself.
deck
deck
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
asked 5 hours ago
DaveInCazDaveInCaz
1,089728
1,089728
3
I can't answer the question as asked, but I can say, after demolishing, repairing, and restoring many aged decks, that the tops of the joists aren't exactly an Achilles heel. If the deck is old enough that the integrity of the fastening surface is degraded beyond utility, so are the joist ends, beam connections, posts, etc. At that point, since the decking is probably being replaced anyway, it's a fairly short step to a total rebuild. Whacking one proverbial mole doesn't yield much extended deck life.
– isherwood
5 hours ago
I'm with isherwood on this one - the tops of the joists are one of the last things that I would expect to fail on a deck. Even the decks I've worked on where the decking was completely rotted off the fasteners, the tops of the joists were almost always sound. Also, if you're using a composite decking, you'll find that most? of them have cups or groves milled into the bottom of them and don't really have a lot of direct contact area with the tops of the joists that would prevent them from drying out.
– Comintern
56 mins ago
add a comment |
3
I can't answer the question as asked, but I can say, after demolishing, repairing, and restoring many aged decks, that the tops of the joists aren't exactly an Achilles heel. If the deck is old enough that the integrity of the fastening surface is degraded beyond utility, so are the joist ends, beam connections, posts, etc. At that point, since the decking is probably being replaced anyway, it's a fairly short step to a total rebuild. Whacking one proverbial mole doesn't yield much extended deck life.
– isherwood
5 hours ago
I'm with isherwood on this one - the tops of the joists are one of the last things that I would expect to fail on a deck. Even the decks I've worked on where the decking was completely rotted off the fasteners, the tops of the joists were almost always sound. Also, if you're using a composite decking, you'll find that most? of them have cups or groves milled into the bottom of them and don't really have a lot of direct contact area with the tops of the joists that would prevent them from drying out.
– Comintern
56 mins ago
3
3
I can't answer the question as asked, but I can say, after demolishing, repairing, and restoring many aged decks, that the tops of the joists aren't exactly an Achilles heel. If the deck is old enough that the integrity of the fastening surface is degraded beyond utility, so are the joist ends, beam connections, posts, etc. At that point, since the decking is probably being replaced anyway, it's a fairly short step to a total rebuild. Whacking one proverbial mole doesn't yield much extended deck life.
– isherwood
5 hours ago
I can't answer the question as asked, but I can say, after demolishing, repairing, and restoring many aged decks, that the tops of the joists aren't exactly an Achilles heel. If the deck is old enough that the integrity of the fastening surface is degraded beyond utility, so are the joist ends, beam connections, posts, etc. At that point, since the decking is probably being replaced anyway, it's a fairly short step to a total rebuild. Whacking one proverbial mole doesn't yield much extended deck life.
– isherwood
5 hours ago
I'm with isherwood on this one - the tops of the joists are one of the last things that I would expect to fail on a deck. Even the decks I've worked on where the decking was completely rotted off the fasteners, the tops of the joists were almost always sound. Also, if you're using a composite decking, you'll find that most? of them have cups or groves milled into the bottom of them and don't really have a lot of direct contact area with the tops of the joists that would prevent them from drying out.
– Comintern
56 mins ago
I'm with isherwood on this one - the tops of the joists are one of the last things that I would expect to fail on a deck. Even the decks I've worked on where the decking was completely rotted off the fasteners, the tops of the joists were almost always sound. Also, if you're using a composite decking, you'll find that most? of them have cups or groves milled into the bottom of them and don't really have a lot of direct contact area with the tops of the joists that would prevent them from drying out.
– Comintern
56 mins ago
add a comment |
1 Answer
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There’s always “Good”, “Better” and “Best” in any construction project. I’ve never seen the tops of pressure treated deck supports protected with “peel and stick” membrane, and I live in a very wet area of the U.S. (We get about 60 - 80 inches of rain each year.)
All of the ideas he recommended in the video you referenced are great, but membrane on the top of the joists seems extreme. In fact, there is a greater chance that rot will occur at the ends of each support, (because water “wicks” into a board far more in end grain than in side grain,) than on the tops of the supports...which he doesn’t mention.
BTW, there is nothing in the Code that requires a membrane on top of deck supports.
answered 3 hours ago
Lee SamLee Sam
10.5k3718
add a comment |
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There’s always “Good”, “Better” and “Best” in any construction project. I’ve never seen the tops of pressure treated deck supports protected with “peel and stick” membrane, and I live in a very wet area of the U.S. (We get about 60 - 80 inches of rain each year.)
All of the ideas he recommended in the video you referenced are great, but membrane on the top of the joists seems extreme. In fact, there is a greater chance that rot will occur at the ends of each support, (because water “wicks” into a board far more in end grain than in side grain,) than on the tops of the supports...which he doesn’t mention.
BTW, there is nothing in the Code that requires a membrane on top of deck supports.
answered 3 hours ago
Lee SamLee Sam
10.5k3718
add a comment |
There’s always “Good”, “Better” and “Best” in any construction project. I’ve never seen the tops of pressure treated deck supports protected with “peel and stick” membrane, and I live in a very wet area of the U.S. (We get about 60 - 80 inches of rain each year.)
All of the ideas he recommended in the video you referenced are great, but membrane on the top of the joists seems extreme. In fact, there is a greater chance that rot will occur at the ends of each support, (because water “wicks” into a board far more in end grain than in side grain,) than on the tops of the supports...which he doesn’t mention.
BTW, there is nothing in the Code that requires a membrane on top of deck supports.
answered 3 hours ago
Lee SamLee Sam
10.5k3718
add a comment |
There’s always “Good”, “Better” and “Best” in any construction project. I’ve never seen the tops of pressure treated deck supports protected with “peel and stick” membrane, and I live in a very wet area of the U.S. (We get about 60 - 80 inches of rain each year.)
All of the ideas he recommended in the video you referenced are great, but membrane on the top of the joists seems extreme. In fact, there is a greater chance that rot will occur at the ends of each support, (because water “wicks” into a board far more in end grain than in side grain,) than on the tops of the supports...which he doesn’t mention.
BTW, there is nothing in the Code that requires a membrane on top of deck supports.
answered 3 hours ago
Lee SamLee Sam
10.5k3718
There’s always “Good”, “Better” and “Best” in any construction project. I’ve never seen the tops of pressure treated deck supports protected with “peel and stick” membrane, and I live in a very wet area of the U.S. (We get about 60 - 80 inches of rain each year.)
All of the ideas he recommended in the video you referenced are great, but membrane on the top of the joists seems extreme. In fact, there is a greater chance that rot will occur at the ends of each support, (because water “wicks” into a board far more in end grain than in side grain,) than on the tops of the supports...which he doesn’t mention.
BTW, there is nothing in the Code that requires a membrane on top of deck supports.
answered 3 hours ago
Lee SamLee Sam
10.5k3718
edited 1 hour ago
answered 3 hours ago
Lee SamLee Sam
10.5k3718
answered 3 hours ago
Lee SamLee Sam
10.5k3718
answered 3 hours ago
Lee SamLee Sam
10.5k3718
10.5k3718
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3
I can't answer the question as asked, but I can say, after demolishing, repairing, and restoring many aged decks, that the tops of the joists aren't exactly an Achilles heel. If the deck is old enough that the integrity of the fastening surface is degraded beyond utility, so are the joist ends, beam connections, posts, etc. At that point, since the decking is probably being replaced anyway, it's a fairly short step to a total rebuild. Whacking one proverbial mole doesn't yield much extended deck life.
– isherwood
5 hours ago
I'm with isherwood on this one - the tops of the joists are one of the last things that I would expect to fail on a deck. Even the decks I've worked on where the decking was completely rotted off the fasteners, the tops of the joists were almost always sound. Also, if you're using a composite decking, you'll find that most? of them have cups or groves milled into the bottom of them and don't really have a lot of direct contact area with the tops of the joists that would prevent them from drying out.
– Comintern
56 mins ago