I have a typical 70s house. 1.5 stories, concrete slab foundation, and an attached carport with an insulated storage room at the far end.
I am considering sealing the carport to maintain a temperature of 5, 10, or maybe even 15°C there. At least frost-free. Anything above that is a comfort issue and depends on the cost.
But questions arise when I go out and look. It is attached to the house gable with a storage room at the far end and a simple wall running lengthwise that starts about a decimeter above ground and is on pilings.
I, therefore, need to frame a new floor to insulate it. The base is asphalt. How do I do this? Air gap?
The wall needs insulation, but what about wind barrier and air gap here? Currently, there is horizontal paneling on the outside and vertical paneling on the inside with a few centimeters gap.
The roof consists of roof decking and felt. Same questions here as with the wall.
And how do I handle the open part under the wall? Should it be open to ventilate the floor? I also need to stop rats and mice somehow. They show up here occasionally.
Here you can see the bottom part of the outer wall with the air gap. And the asphalt floor. I don't know if it's visible, but outside there is grass (moss).
180 degrees from the first picture, this is towards the house gable and the door to the laundry room. Here it is mainly visible that I have some height to use for the floor. I also need to attach the floor somehow to this wall, right?
The entrance to the carport is blocked by the previous owner with a temporary wall in bad condition. I want to redo it and replace the bad door with a sliding door. I also want to use an existing door leaf that I have standing and try to convert it to a sliding door.
I hope you understand what I want to do. I've probably forgotten some facts. But I appreciate any tips on how to proceed and what materials to use.
The more insulation, the less energy needed to achieve desired comfort.
A suggestion for the floor is a bearer in the house wall with floor joists attached with joist hangers, dimensioned so that you can lay foam boards in between. The beams should not touch the ground but provide an air gap. On the beams, you screw strips where the foam can rest. Here you can control the height/insulation level as desired.
The principle for a traditionally insulated wall looks like this, counted from the inside:
Interior surface - Vapor barrier - Insulation - Wind protection (diffusion open) - Air gap - Exterior surface.
The vapor barrier can perhaps be discussed, depending on the level of heating.
The roof follows the same layout except for the wind protection, which is already in the paper, and the air gap needs to be larger. In this air gap, there must also be the possibility for ventilation.
I would have closed up the open part of the wall.
Mice can get in without requiring large gaps, so you need to make it as tight as possible.
If ventilation is needed, you should install some kind of netting.
The same goes for the roof ventilation, so that wasps don't find a nice refuge.
The foam boards are self-supporting, in contrast to conventional insulation, and do not need the same support from below; it's enough to place them on support strips as you said?
Can I place 45x45 on the asphalt with paper underneath and then the floor beams across these and use the 45x45s as support for the foam boards?
It should be sturdier to build from the asphalt and up rather than having hanging floor beams, right?
Air gap in the roof, so I just leave a little space at the top? So if the roof beams are 220 high, for example, and I place 170mm insulation, there will be an air pocket between the insulation and the roof decking of 50mm. But this air pocket would then be enclosed and not ventilated anywhere, how do I handle that? Maybe it could run down into the wall somehow...
The space is around 3x7 meters I guess. For heating, electric heaters or a heat pump will probably be the cheapest option. Frost guard might not work for such large areas.
How much are you thinking the finished floor will add over the current asphalt?
Of course, you could lay 45x45 (or preferably 45x70) under the floor joists as you describe, if the building height allows it and the surface is flat enough for it to work. For the joists, I was otherwise thinking of something like 28x34 (split sparse panel 28x70).
50 mm air gap at the ceiling is spontaneously on the skimpiest side. 170 mm insulation, on the other hand, sounds a bit over the top for the construction.
The roof measurements were just examples, but how much air is needed? The question was how do I ventilate the space?
So it's better with 70mm of air under the floor than 45mm? Does it insulate better or what?
Height-wise, I would actually prefer not having any elevation at all to make it easier to get in through the door. But a few centimeters of elevation wouldn't hurt since you already have to step over the threshold.
Is there anyone here who has done something like this before?
I have had problems in our garage with too small an air gap in the ceiling. It caused condensation which eventually led to wet insulation and a moldy ceiling. I had tried to get at least 100 mm air gap, which you then put vents in the panel for so that the air can circulate.
When I wrote 45x70 instead of 45x45, it was with the 70 lying down. 45x45 mm is often too flimsy in the material. No difference in construction height.
I don't really understand what you mean by the height over the asphalt.
I imagined floor joists of type 45x145 mm with 95 mm cellplast in them. Air gap below and wind barrier above. And then floor decking type 28x120 mm on top. This gives a construction height of around 180-200 mm.
Maybe you can make a slope/sloping surface down towards the door to reduce the height there?
Sorry, but it seems like things could go wrong here. You have a high risk of moisture damage under your floor if you insulate it well. It becomes a form of crawl space you're building with a high risk of moisture so close to the ground. The air gap in the roof must be ventilated, meaning holes in the eaves and preferably at the ridge (there are devices/vents for this). The various moisture risks typically increase the more you insulate. If, for instance, you skip insulation in the floor, that moisture risk almost disappears. This is because you then heat up the ground and thereby dry it out. Instead, focus on a lot of insulation in the roof plus walls. The ground will still never be as cold as the outside air.
It's wonderful if the best thing is to skip framing and insulating a floor. Sounds too good to be true?!
Regarding the roof; when I look up at the ceiling towards the carport's outer wall, it looks like this.
The roof beams are 155mm high. How much air and insulation should I have here? You can never have too much insulation, I understand, so it's the air gap that dictates it. And in every such space, saw into the wall for a vent? That's quite a few vents.
I don't remember if I wrote this before (and while I'm writing this via Tapatalk, I can't see the posts), but the idea is to at least be able to store paint cans frost-free, i.e., 7°C. And it would be nice to have it a bit warmer sometimes when sawing or working on something out there.
Yes, I didn't think when I wrote "nock"... but the same principle applies. I assume the roof slopes away from the house.
If you're only aiming to maintain 7 degrees and use it as a warm storage, you don't need to build an insulated joist structure. But instead, you can lay ground insulation around the carport (under the grass area). This prevents frost from creeping into the carport. You should build the walls all the way down to the ground, and it's suggested to use lightweight concrete blocks at the bottom against the ground.
Sorry, but it seems like this could go wrong here. You have a high risk of moisture damage under your joists if you insulate them well. It becomes a form of crawl space you are building with high moisture risk so close to the ground. The air gap in the ceiling must be ventilated, that is, holes in the eaves and preferably at the ridge (there are devices/vents for it). The different moisture risks generally become greater the more you insulate. For example, if you skip insulation in the joists, that moisture risk almost disappears. That's because you then heat up the ground and thereby dry it. Instead, invest in a lot of insulation in the ceiling plus walls. The ground never gets as cold as the outside air anyway.
Here I think you're exaggerating the risks. There is asphalt underneath, and the surface has been covered by a roof for a long time.
I have seen several similar solutions without moisture problems.
Now I don't want to cause any trouble - But if you build for the opening in a CarPort, it goes from being just a CarPort to becoming a Garage and is thus, as far as I know, subject to building permits. Regardless of whether there is a building permit for a CarPort, it is not the same as a garage.
The risk does not lie in the surface (asphalt in this case), but the problem arises during the seasons when the outside air contains the most moisture. During the warm season, the temperature under your well-insulated crawl space floor can be tens of degrees lower than the outside air. When warm air enters under the floor, it cools down, and since cold air cannot "hold" the moisture in the air, condensation occurs. A similar phenomenon causes you to scrape your car window in the winter. It doesn't necessarily result in moisture damage as long as the condensation has the opportunity to dry up. If you have a construction with little or no insulation, you heat up the air under the floor = drying out any moisture. If you search further about the issues and history of crawl spaces, you'll find examples and more information.
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