Author Topic: Making attic more comfortable  (Read 225 times)

Zola.

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Making attic more comfortable
« on: February 11, 2019, 02:06:03 AM »
I want to start using the attic space a bit more as a room.. potentially a bit of a man cave....currently its pretty cold, dark and uncomfortable.

There is partial flooring in the middle (covering about 1/3 of the floor), which I may need to rip up.

When we bought the house it had very old and outdated insulation (the thin yellow stuff). We removed it all and put in the new type of insulation a couple of years ago which is really thick and is much better.

Currently its just all rolled out in rows beside each other, covering the floor and runs close to the eaves (not right to the edge).

The new stuff actually made the attic roof felt 'sweat' a little bit after it was installed. There is a little bit of white mould on the roof felt in places. After that we installed four vents to let airflow in and out, two on each side of the roof. I was told by the installer that the marks on the felt isnt really a concern.

I was told the new insulation may change the climate of the house initially, but the vents will sort it. I have never scrubbed off the mould, the installer just said he would leave it. Not sure what I think about that...

The new insulation is taller than the joist depth, so to floor the whole area, I will need to raise the flooring height up, so that I can get the new insulation placed in the joist spaces?

Is there anything I should be aware of or careful about?

I am a DIY amateur, so will ask a friend for help ..

Jon Bon

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Re: Making attic more comfortable
« Reply #1 on: February 11, 2019, 07:34:17 AM »
Woah! Lots of stuff here.

You are in the UK, so my info is different but should be generally correct. First off, is this an attic built to minimum specs, or more of an unfinished room with some thought give to use/habitation by the original builder? Feasibility of this depends greatly on that answer.


1. Floor generally attic floors are not designed to hold people/stuff etc. They are designed to hold up the ceiling, and assist holding of the roof rafters. Generally you should not be standing walking on them daily. You might be ok, but running additional ceiling/floor joists would be recommended. This is known as 'sistering' find the same size joist run it the whole length of the existing and nail them together. Gives you 2x as much strength. Find out how big your attic floor joists are and report back.

2. Insulation A - You will probably need to remove the insulation on the floor. You are going to extend the 'envelope' of the house so the attic space now needs to be insulated. The floor insulation is in your way and with the sistering you need to do it is probably best just to remove it.

3. Insulation B - you need to put in rafter vents and insulate the rafters. This is generally pretty easy but it has to be done to make an attic livable, deal with condensation,  and to keep your roof from cooking itself.

4. Venting, you need under eve vent and ridge vents for #3 to work correctly.

5. Light/Temp - you can go as crazy as you want here. I would probably just do a window AC unit. Do you have a window? I would probably do 1 on either side of the attic so you get light and cross breeze.

This is  a MAJOR undertaking. You would need to share a lot more info about the house as well. I am not saying it cannot be done, and as I said my knowledge is US based. Can you share a few pictures? Do you have regular stairs to the attic? I am sure I am forgetting a ton but this can get you started.

J Boogie

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Re: Making attic more comfortable
« Reply #2 on: February 11, 2019, 10:42:56 AM »


Currently its just all rolled out in rows beside each other, covering the floor and runs close to the eaves (not right to the edge).

The new stuff actually made the attic roof felt 'sweat' a little bit after it was installed. There is a little bit of white mould on the roof felt in places. After that we installed four vents to let airflow in and out, two on each side of the roof. I was told by the installer that the marks on the felt isnt really a concern.



I'm having trouble understanding how how the attic roof would be sweating more after the newer, superior insulation was installed.

The sweat could be the result of either the warm air in the attic condensing on the cold roof, or it could be the result of inadequate ventilation giving the moist air nowhere to go.

But your new insulation stopped at the eaves, so it doesn't seem like it would be preventing any airflow... and since it's better, you'd think the attic would be colder than before and less likely to condense on the ceiling...

Also, I'm not sure the white residue is from mold. It seems like it could be mineral deposits left from the dried out condensation.




lthenderson

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Re: Making attic more comfortable
« Reply #3 on: February 11, 2019, 12:17:44 PM »
You need to move the insulation from the floor to the rafters if you want to condition the space. Depending on what type of construction your attic is will depend on exactly how you do it. The most common household attic will have rafters going all the way to the peak of the roof with occasional ties to prevent spreading. In this situation, if you insulated the underneath side of the roof so there is no air space between the insulation and the roof, you don't need any ventilation at all. Some roofs have scissor ties which means there will be an air space between the insulation on the bottom side of the trust and the bottom of the roof and in this case you will still need ventilation. I'm sure there are plenty of Youtube videos and websites that show you how to properly insulate and ventilate (if needed) attic spaces.

It sounds like you didn't have enough airflow in the attic when you put the new insulation in and that caused the condensation on the roof and possibly mold. As long as the problem has been fixed and it sounds like that in your post, mold shouldn't be an issue anymore. If it bothers you, spray it with a bleach mixture and go about your business.

BudgetSlasher

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Re: Making attic more comfortable
« Reply #4 on: February 11, 2019, 06:20:36 PM »
I can tell you what I would do in my attic (which is a future plan). I am in a heating dominate location with snow on the roof for a good part of the year. This plan would bring the attic inside of the insulation envelope and make it a nicer place, though likely only semi-conditioned as I wouldn't be added heating ducts. Adding more insulation on top of the current insulation will only serve to make the attic more like the exterior and less like the interior of the house.

First, I would build/install vents connecting the eve and ridge vent in every bay. This is important with snow on the roof as snow too is a good insulator. That means no matter how well you insulate the some heat will make the insulation to the snow, which means without the venting the snow insulates itself, causing some snow to melt, run down the roof, freeze into an ice damn above the eve, and likely result in water intrusion. The connected vents will carry this little bit of heat away and keep the roof deck below freezing.

Second, I would hang a second 2x4 off of the current framing using plywood supports to increase the overall thickness to allow for R-60. This also will reduce thermal bridging at the studs.

Third, I would hang rigid foam from the new 2x4 and use my insulation of choice between the roof deck and the new foam (likely cellulose here). I belieive that I would go with 2" rigid foam; this would also act as my moisture barrier (facing the warm side of the insulation).

Fourth, depending on the use of the attic, fire code, and the rating of the rigid foam a fire barrier may be needed over it. In which case I would install drywall over the rigid foam.

Fifth, I would remove all of the insulation from the bottom of the attic.

sixth, if I intend to use the attic I would insure that the framing is up to code. I already have a 2x8 framing on what would be the floor, but I believe I would need to sister them all with a second 2x8 to be up to code for a occupied area.

I'd estimate that it would cost me 6,000 to 7,000 USD in materials to properly complete this project in my house.

Note: I already have wiring in place, but if you do this you'll want to get any wiring in place once the framing is done and before the insulation starts to go in.

Also Note: This is my rough plan for a project that is probably 3-5 projects down the road.


You need to move the insulation from the floor to the rafters if you want to condition the space. Depending on what type of construction your attic is will depend on exactly how you do it. The most common household attic will have rafters going all the way to the peak of the roof with occasional ties to prevent spreading. In this situation, if you insulated the underneath side of the roof so there is no air space between the insulation and the roof, you don't need any ventilation at all. Some roofs have scissor ties which means there will be an air space between the insulation on the bottom side of the trust and the bottom of the roof and in this case you will still need ventilation. I'm sure there are plenty of Youtube videos and websites that show you how to properly insulate and ventilate (if needed) attic spaces.

It sounds like you didn't have enough airflow in the attic when you put the new insulation in and that caused the condensation on the roof and possibly mold. As long as the problem has been fixed and it sounds like that in your post, mold shouldn't be an issue anymore. If it bothers you, spray it with a bleach mixture and go about your business.

I was of the understanding the ties in the bottom third locals call them "rafter ties", which are normally the ceiling joist, prevent spreading, while the occasional ties in the upper third of the attic (seems to be every 3rd rafter here) locals seem to call them "collar ties" were to prevent lift. Have I been misinformed?

lthenderson

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Re: Making attic more comfortable
« Reply #5 on: February 12, 2019, 06:38:02 AM »
I was of the understanding the ties in the bottom third locals call them "rafter ties", which are normally the ceiling joist, prevent spreading, while the occasional ties in the upper third of the attic (seems to be every 3rd rafter here) locals seem to call them "collar ties" were to prevent lift. Have I been misinformed?


I have heard both terms referred to them.

OP: The issue of insulating depends on whether you are going to finish above the collar/rafter ties to the peak of the roof and leave the spaced our collar/rafter ties exposed. If this is the case, you don't need ventilation. Insulation is placed on the bottom side of the roof sheathing. If you are going to finish off up to the collar/rafter ties and leave the space between them and the roof non-insulated, then you definitely need to consider ventilation in that space. Like wise, you will have to ventilate behind any kneewall you may have too.

The rule of thumb is is there is space between the insulation and the roof sheathing, you do need to ventilate that space in someway to prevent condensation. If there is no space, no ventilation is needed.

You can google "how to insulate an attic" and there are numerous images that pop up showing different ways depending on attic style and size of the conditioned envelope.