Thanks! I mostly just read on the Roxul package it doesn't promote mold groth, and thought in a basement that may not be a bad thing. However, I think that is what my vapor barrier does isn't it? I do have a whole house dehumidifier servicing the basement only keeping it at 50% humidity at the most. but I can actually kick that down to like 40% if I need to.
Basement Framing for HVAC
- Thread starter jjohnston
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Help Support House Repair Talk:
nealtw
Contractor retired
Any time this stuff comes up the is usually an argument.
So this is my opinion, and others my have a different one.
In a living space you try to create a weather system so that warm air replaces cold air. If warm moist air contacts a cold surface the moisture can condense and if the food is there mold spores can start to grow.
So we want insulation so we don't have cold surfaces. But if there are gaps that allow air flow thru the wall we can get a weather system in the cavity or behind the insulation.
Usually we insulate the wall and apply the vapour barrier to stop the air flow. In your case you will have a vapour barrier behind the wall and you should not have any more problem with that than any other interior wall .
We don't concern ourselves about the insulation we add to interior walls for soundproofing. Most cavities in the house are closed with drywall and painted, And paint does have a value for vapour barrier, not much but enough to keep interior walls dry.
So this is my opinion, and others my have a different one.
In a living space you try to create a weather system so that warm air replaces cold air. If warm moist air contacts a cold surface the moisture can condense and if the food is there mold spores can start to grow.
So we want insulation so we don't have cold surfaces. But if there are gaps that allow air flow thru the wall we can get a weather system in the cavity or behind the insulation.
Usually we insulate the wall and apply the vapour barrier to stop the air flow. In your case you will have a vapour barrier behind the wall and you should not have any more problem with that than any other interior wall .
We don't concern ourselves about the insulation we add to interior walls for soundproofing. Most cavities in the house are closed with drywall and painted, And paint does have a value for vapour barrier, not much but enough to keep interior walls dry.
This is weird. The inspector got back to me and said r-5 insulation on inside wall max since builder did r-10 outside. I replied back asking if he meant min, but haven't heard. Have any of you heard about a max for insulation? I can get r7.5 cheaper than r5
nealtw
Contractor retired
I think he was stating min, and yes you can do more.
Ok, he kinda lost me a bit. Below is what he saud.
Exterior meets code with exposure and air changes per hour. You can insulate on interior Max. R-5 seal with tape and at edges with 2x4 wall in front. Any foam would not be exposed. If exposed, Thermax could be used and leave exposed.
Exterior meets code with exposure and air changes per hour. You can insulate on interior Max. R-5 seal with tape and at edges with 2x4 wall in front. Any foam would not be exposed. If exposed, Thermax could be used and leave exposed.
nealtw
Contractor retired
That needs clarification unless both look the same and who would know.
The other part is that the foam wants to be covered with drywall for fire protection.
The other part is that the foam wants to be covered with drywall for fire protection.
He can only quote you min. standards for your climate zone.
KULTULZ
JACK of All Trades ~ MASTER of NONE
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My fear is the galvanized rusting or flash rusting in a humid basement. Not true?
True, in an unconditioned space, maginaly fit for occupancy, eventually, and the fact remains that the repair is far and away, simpler to accomplish then with wood.
I heard back from the inspector. Here is what he says in regards to the R-5...
The code has changed for foundation insulation over the years. More is not always better. Too much insulation restricts heat loss through foundation. It was found that this could cause the earth to freeze and cause more pressure against foundation. With the R-10 on exterior, I would not go with more than 5 on the interior. I would avoid using fiberglass on interior because if any moisture did come through foundation, it will wick through fiberglass unless a good water proofing is applied.
The code has changed for foundation insulation over the years. More is not always better. Too much insulation restricts heat loss through foundation. It was found that this could cause the earth to freeze and cause more pressure against foundation. With the R-10 on exterior, I would not go with more than 5 on the interior. I would avoid using fiberglass on interior because if any moisture did come through foundation, it will wick through fiberglass unless a good water proofing is applied.
nealtw
Contractor retired
There you go, we get to learn something.
nealtw
Contractor retired
And that why I said it needs clarification. That might be code every where with deep frost and CMU. We don't see CMU foundations here. just seismic concrete.
And our frost level is only 18 inches.
It sure is something to keep in mind.
Thanks Everyone!
I know every place has different codes, but the information I have been given in this forum has given me HUGE help, and without it, I think the 4 questions I had for the inspector would have been more like 4,000. I ordered my lumber today. I also heard back from the inspector that I can go less than R-5 (he didn't say how much less) made it sounds like my code was fulfilled by the insulation on the outside, but I did ask him to be sure. I am planning on doing 1/2" R-3 rigid insulation and tape the seams to still have a vapor barrier, but doing that is saving me a LOT.
I know every place has different codes, but the information I have been given in this forum has given me HUGE help, and without it, I think the 4 questions I had for the inspector would have been more like 4,000. I ordered my lumber today. I also heard back from the inspector that I can go less than R-5 (he didn't say how much less) made it sounds like my code was fulfilled by the insulation on the outside, but I did ask him to be sure. I am planning on doing 1/2" R-3 rigid insulation and tape the seams to still have a vapor barrier, but doing that is saving me a LOT.
nealtw
Contractor retired
It does make sense that the builder would have insulated to code.
OH, is 1/2" XPS insulation ok for the walls as a vapor barrier? or do you all think I'm better off skiping all together? when I go to the basement it is definately MUCH colder than the upstairs even with the 4 heat vents installed already. (after I finish it will be 12...)
nealtw
Contractor retired
If you have heat at the ceiling and heat rises, you have more returns and register up stairs, it does make sense that the basement is cold. That will be a problem even when you have everything done you will likely have to adjust the upstairs registers to force more air to the basement. Obviously they do want some heat lose to the foundation. If you want to skip the foam you would put a vapour barrier between drywall and framing.
BTW. If you are using a shower pan or building your own you need a kick around the bottom, 2 x 10 blocks between the studs to give solid backing for backer board. If it is not to late to add a 10 ft 2x10 to the order.
BTW. If you are using a shower pan or building your own you need a kick around the bottom, 2 x 10 blocks between the studs to give solid backing for backer board. If it is not to late to add a 10 ft 2x10 to the order.
And had you submitted your plans for plan check, most of your question would have been answered, rather than rely on information totally geographically unrelated.
There is another subject that hasn't discussed.
Is you existing comfort heat appliance of sufficient capacity to handle the increased load and will the existing blowers be sufficient to maintain comfort heating throughout?
