I have just ordered a Granab subfloor with mechanical ventilation for our recreational room. Since I have awakened a previously dormant interest in handiwork during the planning phase, I also plan to lay the floor and install the ventilation myself. Mostly because I'm cheap, but also because I’ve realized that I find it really fun!
Since we want the lowest possible building height, we cannot have any insulation between the joists to ensure sufficient airflow under the floor. Although I don’t really understand why you would need insulation since you’re channeling warm air under the floor. I will, of course, install a moisture barrier between the joist and the chipboard. One thing I’m pondering is how the moisture barrier will hold now that it can't rest on the insulation. And you can't glue chipboard to the foil, foil to the joist. So you resolve it by simply screwing the chipboard to the steel joist while stretching the foil, or?
Since we want the lowest possible building height, we cannot have any insulation between the joists to ensure sufficient airflow under the floor. Although I don’t really understand why you would need insulation since you’re channeling warm air under the floor. I will, of course, install a moisture barrier between the joist and the chipboard. One thing I’m pondering is how the moisture barrier will hold now that it can't rest on the insulation. And you can't glue chipboard to the foil, foil to the joist. So you resolve it by simply screwing the chipboard to the steel joist while stretching the foil, or?
No, absolutely not. It serves no purpose. Perhaps rather the opposite. I interpret it as you wanting to ventilate the floor because it is cold/damp. The moisture probably comes from within unless it is rising ground moisture that is drawn capillarily into the slab. The question is whether it is appropriate at all to blow moist warm air into that space. The risk is that it just condenses on the floor. It is probably much better to extract air from the space.tobee said:
I have personally worked with Granab in multi-residential projects. Currently, about 14,000 square meters in the current project. There are several different applications for this floor. You still haven't explained why you are going to install this floor.
Reading the instructions, it then becomes clear that it is about exhaust air from the floor and not the other way around. Therefore, the foil might be okay, but hardly necessary. Insulation is used to have a warmer floor if you have a cold, likely uninsulated, basement slab underneath.
Reading the instructions, it then becomes clear that it is about exhaust air from the floor and not the other way around. Therefore, the foil might be okay, but hardly necessary. Insulation is used to have a warmer floor if you have a cold, likely uninsulated, basement slab underneath.
Moisture is indeed absorbed capillarily, the basement walls are uninsulated on the outside and so is the slab. Therefore, I had odor problems in the previously insulated wooden structure. However, the air in the basement recreation room has always been quite dry. Both I and the previous owner have used a dehumidifier that keeps RH 50-60% even during the hottest summer days. Now I've had the basement recreation room completely free from wood for a year and it has been completely bone dry even without a dehumidifier. Not a day over RH 70% except for the day when I plastered the basement walls =)
I'm really just doing as I have been recommended by moisture technicians from OCAB. Simply put. As little organic material as possible. Underfloor with negative pressure. Plastered basement walls. Then my moisture problems should be a thing of the past =) Condensation? Yes, maybe, but what does it matter if I have steel studs and a plastic film protecting the chipboard? That's why I chose Granab over Nivell! Cheaper too.. Then I'll have an RH meter by the exhaust fan. If the RH starts to creep up, I'll use the dehumidifier =)
Why would a plastic film cause damage?
I'm really just doing as I have been recommended by moisture technicians from OCAB. Simply put. As little organic material as possible. Underfloor with negative pressure. Plastered basement walls. Then my moisture problems should be a thing of the past =) Condensation? Yes, maybe, but what does it matter if I have steel studs and a plastic film protecting the chipboard? That's why I chose Granab over Nivell! Cheaper too.. Then I'll have an RH meter by the exhaust fan. If the RH starts to creep up, I'll use the dehumidifier =)
Why would a plastic film cause damage?
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