Hi,

I bought a house built in 1948 which is missing insulation in large areas. I have been posting on here for a while trying to figure out what kind of home I own and found out that "1.5 story homes" are a pretty common thing here. To me I just look at it as if someone converted an attic to obtain more living space. Anyways, there are 3 tiny bedrooms upstairs that average about 100-150 square feet.

I would like to know how to insulate the rooms properly. I don't want to spend money by insulating areas that aren't necessary or where there is little to gain. I also don't want to go with blow in insulation at this time because the drywall in this home likes to crack.

I know that I must obviously insulate the outside wall and that is just fine with me.

However, I am somewhat confused beyond that.

I have placed a drawing below illustrating my understanding of where I believe that I should insulate and the areas where I have no idea on earth as to whether or not I should insulate.

As for the blue airbrushed areas below: I am confident that this is where I need to insulate.

After this I am completely lost. Once I crack the kneewalls open, I can get to the areas in red. Do I insulate those areas?

What about the areas in Green? I can reach those pretty easy.

The areas in brown are the few inches between the kneewalls and the very top area (top triangle). I can not see being able to insulate this area unless some rigid pieces of insulation were put there and I would guess that area needs to breathe?

The areas in purple are difficult to reach as well because that would require popping the drywall open in the ceiling, going through existing insulation above the ceiling and no more than 2 feet of working space.

Could you all guide me through exactly where I should and should not insulate?

Remember, these rooms are very small but the kneewall area can be reached pretty easy.

Please make this simple and easy to understand. I will more than likely become VERY confused if you use any sort of terminology at all.

Finally is R-13 ok in the blue areas? What about the other areas if they apply?

Thank you!

 

Recommended Levels of Insulation : ENERGY STAR
You only need to insulatate the areas in blue.
You have to make sure there's not insulation sitting out over the soffit vents, the insulation should only cover to the outside walls.
There is going to have to be a ridge vent on the roof.
There's also going to have to room left at the top sides of your room walls to roof area for air to be able to come in the soffit vents and out the ridge vent.
If you ever want to almost double the size of those rooms you could have someone make the rear roof line into an expandable cape style roof. It would be like adding one long dormer across the whole roof. It will add a ton of space and light into the room.

 

Go to buildingscience.com. They have a bunch of information about insulation and other things home related. I found it to be very useful. I think it's Bud who has another good link for your specific situation which is very helpful. I'm sure he will be along and share it.

There are a few ways you can insulate. One of the way is basically what you propose. If you insulate the blue areas, you need to insulate the red areas. You also want to block the floor joist bays where the red and blue meet to prevent air from flowing below your living space. You need something solid like wood or foam board and caulk to the gaps around. Batts do not prevent air flow.

Do you have soffit vents? If so, make sure you do not block them when you insulate the red areas. Another way you can insulate your second story is to insulate under the roof which would be your green, brown, and purple areas. If you go that route, you need to maintain at least a 2 inch air gap between the insulation and the bottom of the roof deck for air flow. You would also need to have adequate soffit venting and upper roof venting.

If you are using faced batts to insulate, keep the paper face towards the warm side which would be your living area. That is important.

 

Thank you for the responses. I am really lucky that you all understood what I was talking about.

Anyways, this brings up a few new questions:

I prefer to go the first route by far. I just want to insulate the inside area for simplicity. So is it just the blue areas or red and blue areas that need to be insulated? I know that outer walls (for a money pressed person like me) are generally R-13 due to space limitations of the studs. Does the levels of suggested insulation still follow an attic because it is really nothing more than an attic and because I have more space to put the installation down? Why wouldn't I just follow the same levels of insulation as I would for any other outer wall in my house? Again is it simply because I have more room?

Also, yes I do have soffit vents. Thanks for all of the other info!

 

You want to treat the ceiling of the blue area and the red area as attic spaces. The walls of the blue area are treated like any other wall of the house. Get as close as you can to the recommendation in those ceiling areas. If you have 2x4 studs, use R-13. I think the requirement for has been increased for walls up to r-19, but if you don't have the means to fit it in the wall, there isn't much you can do. You could put in unfaced batts and then put a layer of rigid foam on the outside of the studs.

 

I think he needs to remove some drywall to access those areas so he can insulate.

 

You know what guys...thanks for all of the help but my previous drawing was slightly off.

Not sure if it makes a difference Notice that the living area is not really a square. The walls come at 45 degrees to met the roof. The areas where the walls come to meet the roof at 45 degree angles go for about 2-3 feet and are unfortunately about 6 inches from the roof.

Could you all please take another look and tell me if the exact same scenario still applies?

Thank you

 

Hi jj, I've been out of town so a bit late, but the link drooplug mentioned is below. I haven't read through the posts above, but insulation and ventilation are your objectives. My area is a lot colder than yours, but my upstairs is the same and I'm doing a step by step upgrade to reduce my heating costs. You won't need the extreme steps I'm taking, but more is always better than less. I'll be back with more time tomorrow.

Bud

Welcome To Home Energy Magazine Online

 

Awesome, thanks very much Bud!

 

Also, my question still stands as to whether or not I would need to insulate the brown areas in my new drawing. If so, how on earth do I go about doing that without taking the drywall down. Is it necessary? There is only like 4-6 inches of space between the roof and the drywall there! Sorry to get the drawing wrong the first time but I still need help!

I plan to insulate the blue and red areas as one of the two possible options. (Lets call this method 1 for simplicity). I can get to the blue and red areas but I REALLY need to know about the brown areas in my second drawing. Do I need to insulate there and do I need to pull the drywall down to do it??

Finally, The arcticle shows that I need R19 for the kneewalls and attic floor but the other arcticle says R38 - R60 since my area is in Zone 4 this is a massive discrepancy and I don't want to purchase the wrong insulation.

I need to start this project soon so any thoughts are appreciated.

Thanks!

If I am confusing anyone, I need to know if I need to insulate the area within the brown circle if I am going to insulate via method 1 (insulating attic floor and knee walls).

Come to think of it, don't the top attic and side attic need room to "breathe" at that part?

 

The answer is yes, the area in brown does need to be insulated. At issue would be whether you call it a wall or a ceiling to determine the amount of insulation needed. In either case, the limiting depth won't allow you to meet either standard, so you do the best you can.

Options are to slide some batt insulation up in each cavity. I would use 3.5" mineral wool, that's not fiberglass as it is much denser. That would leave a 2" air gap on top for venting. I'm assuming you have soffit vents at the eaves and then gable or ridge vents in the upper area.

The other critical area is under the knee wall. You need some sort of air block to prevent the cold air in thode side attic spaces from flowing under the wall and under the floor of that room. Essentially between the ceiling below and the floor above it.

As for how much, local codes will vary and new energy codes may have changed a bit, but way up north we use less than the 38/60, even though I like those numbers. If your walls are 2x4 you are only going to get max of 15 in there. If 6" walls then the 19 will fit. To get numbers above that, you need to add more to the walls or cover them with a layer of rigid foam board, inside or out.

One more option for the brown area would be to glue a 2" layer of rigid over the drywall on the inside and then add another layer of drywall over it. Basically the same as removing the old drywall, just a little less mess.

Bud

 

Spot on Bud, I am thankful that you own a home like me...misery loves company j/k. What about radiant barrier for that area (the silver bubble wrap stuff). I did that for a section of that area in one room. I don't think that was a smart move but I figured I would just ask.

As far as the 3.5 inch mineral wool...that is an awesome idea! Is it rigid and can it be slid in there without removing the drywall once I have access to behind the kneewall? Also your other idea on gluing the 2" layer of rigid on the inside. I am not going to ask if it is rigid lol but I am going to ask what kind of glue and why I couldn't just slide it in there when I am behind the kneewall and why I would have to add drywall agin.

Almost there and thank you!

 

You can slide in some rigid, but it becomes difficult to get an air tight fit on the sides. The batt mineral wool is just a bit oversize and with a trick or two it can slide right in. Bend up a rectangular sleeve that will hold the batt in a compressed state and will also fit up into the cavity. Slide it in, use something to push on the batt while you slide the sleeve out. I have also created a simple "T" on a push stick with some nails so I could push the batts into place and work the push stick back out. The only real obstacles are the nails from the roofing above.

The bubble back provides some warm weather benefit, but minimal cold weather. Much less than what you need.

Construction adhesive works for me, but check to be sure anything you select is compatible with foam. The polyisocyanurate, foil on both sides is r-7 per inch and the foil would work with most glues. The trick becomes nailing the sheetrock up as the last layer. requires 4 1/2" nails and you need to mark the studs before you start. I used 4" drywall screws.

If you install batt insulation in the knee wall, you should not use faced on the attic side. You should use wires to hold it in place and then cover the back side with tyvek so it doesn't act as a vapor barrier.

Bud

 

Thanks for the info...I think I have enough to go on here. One last question....can't I use spray foam to seal the area where the kneewall meets the floor? I recall seeing that at some URL but wanted your opinions.

I think other than that part I am set.

Oh by the way...are all of the types of insulation you mention available at a big box store like Lowes?

Finally, I found some rock wool insulation in the knee walls in some locations. I have googled it for hours and I guess my final conclusion is that it does not contain asbestos. Any ideas on whether or not to keep it in there or add to it...use it somewhere else like maybe at the roof line areas or dispose of it?

Thanks for all!

 

Google Roxul to check the modern version. This stuff is relatively new, so what you have is unknown. When in doubt take it out, it isn't that expensive and you eliminate any future concerns. If you suspect asbestos, you need a pro and a certified removal to be able to say to someone in the future it was taken out properly. FYI

By under the knee wall I'm looking at the 8" or 10" cavity below the floor the wall rests on. I suppose can foam could fill a space like that, but it is not intended for thick applications and may not cure all the way through. You would also not want it to expand and push up the ceiling below.

Does your knee wall rest on a plywood floor where you cannot see the cavity below or is that cavity open to the side attic space? It is that cavity where the insulation should be going, not the floor above, just as your drawing shows. From your drawing, use a piece of rigid foam board or wood blocking right where you show the insulation stopping under the wall.

If the block you install doesn't seal completely, then some can foam can be used.

Bud

 

The reply is simple.
Keep in mind that heat always moves to cold.
And that you want the heat you have paid for to stay in the room.
Heat is mainly lost through holes and cracks.

You should line the walls and ceilings with three or more inches thick polystyrene sheet. Taking care not to leave any cracks that your warm air and water vapor can escape through.
Add finish of choice.

 

I'll have to check into all of this but thanks for your help Bud.

 

What's this polystyrene sheet you are referring to? Are you suggesting that I use that stuff instead of insulation or in addition to it? It gets hotter than even Lake Wales, FL in the summer here too. (I have lived in that area which is rediculously hot too).

 

Polystyrene generic name was brought to market 51 years ago by Dow called Styrofoam/Blueboard.
It is the best generally available insulation, giving you the best priced results per inch of thickness.
Polystyrene is a closed cell insulation that is 98% air and 2% plastic.
It is waterproof and windproof, it is not effected by ice or heat (it starts to melt at 340C.
I have eight inches of polyurethane (almost the same product, a bit more difficult to find, a bit more expensive) in my ceilings) and it works fine.
Now days, things have moved on and the current best product is SIP,s a sandwich of Oriented strand board or plywood with polystyrene in the middle.
You can buy this made to measure, getting the whole side of your home in one piece, with holes for doors and windows, you just stand it up and join it together, no frame required.
SIP's makes building very easy and produces a home with few cracks to let out the heat (or gain heat) joins are sealed with foam.
Make a roof and walls of this and you can be sure that the inside will be cheap to run.
End of rant!
You can fit polystyrene sheets over the outside of your frame or over the inside, doing the inside is easier, you use less insulation and retain the outside appearance of your home.
It is easier to seal the joins working on the inside and you don't have to bother about the weather.
When you have completed the ceilings and walls add a floating floor.
For a good result cut the polystyrene to a tight push fit and fill the gaps between the sticks, joists and rafters then add a tightly butted layer over the outside or inside to stop the heat moving through the frame, the frame amounts to 1/8th of the surface and gains/looses most of your heat by conduction.