Finished attic mold remediation

[TideWater]

Our finished attic has a partial ceiling with an air duct in it. This part of the house is probably cir. 1840, renovated 1995. I don't think there are any vents in the roof. There's mold on the ceiling and some of the walls. I think it's probably from condensation on the ductwork. We're going to have a mold remediator rip everything out and we're having the roof inspected too. But I have some questions about what to do while the ceiling and walls are open. My plan is to have the ducts wrapped with appropriate insulation and to have Rockwool/roxul batts put in between the rafters. Then we'd have a hatch put in the new ceiling for future inspection. Does all that make sense? Any other suggestions?

[Gothichome]

Hello Tidewater, first off, welcome to the District. We like pictures, of the old home type of course.
An 1840’s home, we have several members with homes of this vintage, they may chime in as well.
But back to your issue, it sounds like they left no room for air movement in the space above the drywall. Condensation from the vents as you describe is a most probable cause. Ripping it out as you are doing I think will be your long term solution.
I would recommend not insulating the rafter space against the roof planks (or has it been sheeted over?). The problem with insulating against the roof is will retain moisture against the roof deck. Every thing in the cold zone needs to have air movement, it keeps the under side of the roof dry and free of rot. Can you explain the actual configuration of the attic room. Is it a proper ceiling with walls or a slanted roof using the rafters as the nailing studs.

[phil]

rock wool has good sound blocking abilities but if you want to increase the R value you might look into ISO board. perhaps you could even add that into the dead space on the inside of the studs and still use the rock wool. not trying to sell you on a product but you cn discover the different insulation options. I prefer rock wool to fiberglass and not much price difference, but there are other products that provide more R value.

your roof should be vented, if there isn't enough venting then you can simply have a roofer add more roof vents. this does not require a new roof. gable venting is another option. if you plan to re roof you can look at ridge cap vents or they can be added. since shingling finishes at the peak it is not that difficult or hard to work on that and reconfigure it a little

you could explore the option of a fan that blows air outside, and that could be turned on and off by a humidity sensor. it may also expel excess heat by being turned on by a "reverse thermostat".

some like the whirly things that go on vents , some say they make noise, some dont feel the appearance fits well with a heritage home.

there is a formula for the square footage and the number of square inches of vent. a roofer or insulator may advise on that better than I can. If there is no fan, you just may need more venting area, but both should be options.

Ideally the air enters near the bottom of the roof, then travels up under the roof to vent out the top, this helps cool the roof deck. as pointed out if your roof deck is insulated then it runs hotter and this can reduce the life expectancy of your roofing.

you can get insulated material that go up between the rafters, they are wavy things made of Styrofoam that allow heat transfer above but still allow some insulation to flow between the roofing and the insulation. some dont recommend insulating the roof at all, but instead insulating the floor of the dead attic space.

can you consider that space as dead space or can it eventually be a part of your living space? Many old houses were not originally configured to actually use the attic space but were converted to increase space. although the ducts are there it still might be an option that you dont want to prevent, at least eventually, from happening.

heat ducts themselves should be sealed and they are usually warm so you might look further into where the humidity is originating, perhaps you can add bathroom fans if they dont exist or a hood fan that blows outside. baths and pots boiling generate humidity but perhaps some of this relates to the environment the house lives in , some old houses have wet basements too.

[TideWater]

I had a roofer here today. He does a lot of work on historic homes and said we need roof vents but that I shouldn't install them until we're ready to replace the roof, which he doesn't think is necessary yet (and my wallet isn't ready for either). Fortunately, he did find some soffit vents. They're painted over but that's easily fixed. And we apparently do have that styrofoam thing you described for ventilation.

The room has low walls on both sides--about 3ft high (knee walls?)--then the ceiling is angled until it reaches a flat section below the peak. I think it's basically shaped like an "A" with the room in the lower part below the bar and the triangle at the top sealed up. I don't know what's in there so I guess we'll have to hold off on finalizing plans until we open it up. The roofer was pretty sure that the mold comes from the ductwork and internal humidity rather than a leak. He noticed some warped shingles near the peak of the roof and explained they were likely a sign of moisture coming through the roof from the interior.

[phil]

it sounds like the configuration of your house isnt' much different than mine and that the roofer is being straight with you.
if you only have a gable vent you can always put a fan to temporarily increase flow before more is done.

in my house what they had done was to lift the roof a bit on one side, that extended the roof 4 feet on one side of the kitchen, then they made stairs down and overtop of that stairs up to the attic. that was probably done not long after it was built. originally it had a separate entrance for the basement. to do that they did cut one beam but the two staircases do provide some additional structure so it was well executed. It's very square and plumb and I have a foundation about 2-3 feet tall. i believe the foundation is original but the basement floor was profesionally finished. the basement is a bit low, but walkable , it would be a project to dig down but there is potential to dig the floor down , underpin the foundation , build 2x6 walls and make the basement a legal suite.

so when I got it it had the A shape you describe with the low walls and the space behind those walls was dead space full of dust.

I installed 4 doors for access to the space and put painted plywood down there and insulated the walls. I have about 4 roof vents. ( just did the roof and added more. one I strategically placed above the bathroom so it can be used to install a bathroom fan. I installed one gable vent with an octagon shape. I insulated the floor before the plywood with roxul. I moved the framing about a little to incorporate the doors but kept the structure intact. It gives me a triangular space the length of the house and 6 feet wide , for storage. i had some big drawers in there as well and I left those. Ive seen other houses where they put a series of small doors and cupboards for storage. nice if you cna use the space. with the doors I can go in and inspect easily, but there is drywall and some insulation above the living space.


If I examine the structure of my house, it has big timbers in the basement supporting the floor in the middle. above that it has some walls which are load bearing and it has the low walls you describe above that so that forms part of the structure, There are no trusses.

it sounds like in your house they my have used this low space for venting and in mine they put some distribution ducts in the basement. they have to go somewhere. Originally it had a heater in the basement in the middle of the house and a grate in the floor so the heat simply raised from the burner through the grate with no air returns. the basement had leaky walls and maybe that was intentional. I added some drywll and insulation which made my basement more comfortable and reduced the "chimney effect"
later with forced air they made it so the heat comes up near the outer walls and there are some air return vents near the center of the house. Its common in old houses to see these changes as they weren't built originally to incorporate the ductwork. often these sorts of renos create weird situations. Ive seen a lot of houses divided up and suited in weird ways. Im in the city and real estate is valuable so most houses like mine have occupied attics. with a lot of them they put the whole house on beams while thy completely replace the foundation , make it taller and lift the house a foot or so , sadly they usually also destroy the heritage in the process , remove the chimney and strip it down so it's almost just bare studs, add all new windows and siding and create essentially a new house around the old stick frame. often they are built close to the front street leaving a big back yard and modern houses have more setback so they sometimes want to call it a reno and not move the house. Ive heard of people going to the extent of leaving only one or two walls to call it a "renovation". they also often pick up houses and move them ot other lots. on one they even moved three houses aside , built a parkade and plunked the houses back down on top. at least they saved the heritage houses.

I use my attic as our bedroom it has two small closets at the top of the stairs that ascend from the kitchen, there is a funny U shaped room which is a bit weird but the head space for the stairway robbed some space in that room. If I was to reconfigure it from a point further back or if I could go back to the start when I bought it one change would be to elliminate those closets and leave the space a bit more open because there are no dormers so the windows are only on the gable ends. I think that would give a bit more of an open feeling. I would not move the low walls as they are structural. adding dormers would allow a bathroom or more light but that's another big reno.

my kitchen is at the back of the house and there is a balcony and steps down. originally it had a staircase within the kitchen area but they moved the kitchen ( back) door and added the porch and steps down from that. my counters faced the back yard. I reconfigured that so the cabinetry does not go against that gable wall so that the house could be extended out the back. i could add on 30 feet on the back, or maybe a future owner could. preserving the potential may help the value. It was niocer to do the dishes facing the back yard instead of the neighbors house, but i could still change that.

if you had a chance to tour some similar houses you might note what changes were made and use some ideas your like or keep them in mind as you may wish to use that space at some point or at least keep the potential for a future owner to open it up.

my stairs up are probably not legal by todays standards as they are quite steep but it's grandfathered at this point. If I did do a major renovation involving the structure the city would probably make me change that. to me it's fine it just adds some character. the stairs were painted and I stripped all the paint and restored the nice fir woodwork it has.

here is a short video that shows a roofer installing a vent in an existing roof. It shows how easy it could be. I think this is within the scope of your roofer but he may have just not wanted to risk a leak this time of year. sometimes when you dig into things you find it needs more and it's best to choose that battle in good weather.
you can note that roof has shingles but no membrane and most roofs here that are replaced use a membrane which is thin cheap and adds some security against leaks and also security against a storm that could happen during the roofing job.
It took me alone thre sessions of summer holidays, by comparison it took a roofer next door a week to do the whole roof with about 5 guys. they did however introduce a strange lump which I think was caused by them not removing all of the old shingles.
roofs can be layered up to about 3 layers so if it is flat and you catch it in time you may opt for that. its nicer to strip the old roof. I also added drip flashing on all sides, that keeps the edges of the plywood dry. the flashing above the gutters helps ensure the water gets into the gutter and it cant' be seen. in some modern houses they use great big flashings. I didn't mind the 2" ones but 4" flashings would change the look too much for me.

origionally my house had wooden gutters they were supported by the gable end fascia boards and I still have the notches to prove that, later it was updated to metal gutters with small fascia boards nailed to the open rafters behind the gutters.

when you go pulling shingles off you can see the plywood, mine had shingles or shakes originally, maybe yours still does. often they remove the wood shingles and sheet with plywood. you may have to make a decision to go with a cheaper modern ashphalt shingle roof or a more authentic roof like cedar shakes. I'd consult with the roofer on how long to wait and what to do there.

if you just look up from inside your atitc you will see strapping that was used to suport the shakes if that's what it had. If you do not see plywood ther and it has shakes then you probably had no plywood either. so if you went to re roof you could install plywood or go with shakes again and not need plywood. good cedar shakes last a long time' they can far outlive a duride roof, but that is probably more expensive. mine had been already changed over so it was pretty much a no brainer to keep it like that but the look of shakes is nicer. some like metal roofs I dont myself, but they do last.

one further option is to strap the roof and put another roof overtop leaving a space for air to enter between the roofs and exit out a ridge vent. yes one roof right over the old one. then you need bulkier flashings but this would improve heating and cooling efficiency. mine had plywood already so I just needed to change the area over the kitchen because it was old shiplap . I just added a layer so my roofing nails wouldn't hit the gaps in the shiplap.
If you start opening things and see wood bugs and things you may see better but the roofer will probably advise on what he expects to see there. I found the odd silverfish scattering out where the wood was bad but the membrane and new plywood where needed seemed sufficient to solve any infiltration. my attic is bone dry and we see tons of rain here but we do not get high humidity like they do out east. I did not need to replace all the sheeting.

here's that video link .
https://www.youtube.com/watch?v=uZ3s7R85Cts

[TideWater]

Thanks for the link. I'm pretty sure my wood shingles would splinter into a million pieces if I tried to do that. So probably best to wait until I'm ready for a big job. Unfortunately there are no gable vents either. I'm not sure what they were thinking when they renovated the house. They put new cedar shingles on around 1995. The roofer said a good cedar shingle has about a 25yr life so we're stretching it.

Below I added 2 photos looking inside the doors in the knee walls.

.

[Lily left the valley]

Welcome to the District.

FWIW, the plastic airflow device attached to the roof sheathing is know as an insulation baffle. Sometimes if floppy insulation (like pink fiberglas batts) or blown in/foam isn't installed right, it can cover/fall into the top opening which kinda prevents it from doing its job.

We found dunken weasel roof work done before we bought our home where a ridge vent was added, but no soffit vents. What made no sense is the home already had perfectly functional almost perfectly east/west gable vents--so there was no need here in New England to cut into the roof for a ridge vent. That'll get fixed when we do end up needing to reroof.

See if there is a bath/kitchen/dryer vent that is venting into the attic instead of through the attic to the outside. Sounds insane that someone would do this, but I've seen it more than once on various sites where they're fixing humidity issues. If there is venting through, check the seams to make sure they're not leaking humidity into the attic.

If you haven't already, buy a basic hygrometer so you have an idea of how moist the air is in your home. If it's above 70%, that's not good. Most references state 30-50% as ideal these days (I think 50% is what the EPA determined was when mold is more likely to start forming), though my old timey vintage hygrometer encased with other useful devices says the "comfort zone" is between 50-70%.

Also check the grading around your foundation--if it's not properly graded or plants are too close, that can boost the humidity too with water intrusion. We have been working on that at our place, and the mostly dirt cellar isn't helping keep the humidity level more ideal either.

Lastly, check if your chimney chase has metal flashing around it in the attic and cellar or not. If not, it can pull moisture and warmer air from the other floors below.

Keep us updated on your progress!

[Gothichome]

Tidewater. I was going to suggest to install exactly what is already installed to vent the roof deck. Although it does’t look like enough has been installed, I would suggest doubling the insulation baffles in each rafter space. As far as condensation from the heating vent, if you can incorporate it into the heated space rather than the cold space. There would be no more issue with condensation. Also vents Anne added in the soffit to line up with the barriers an a ridge vent n the peek to allow free flow out of the building.

[phil]

If the rafter space between the door you show and the peak is stuffed than there may not be a good way for heat to get past. I put some vents in the roof above this triangular storage space for that reason. I did put some near the peak as well.
I think it is hard to know "exactly" what is the right amount of ventilation as it will also depend upon your local climate and weather patterns.
Yea if it has shakes that might be a little more involved. Id check with your roofer. maybe gable vent are enough.

i put a box, lined with metal in there with an AC unit in it then I collect the air from that space send it through the box and outside and also the unit collects fresh air , cools the fresh air from under the eves, and sends it into the bedroom. a little bit complicated but it works and that evacuates all my heat wen it's actually running. I control it with a remote that can shine through a window in the box. you could also use a "portable " ac unit. I sort of made my own
I dint want o block my windows with a window rattler and this way the noise is kept behind the door and the short wall which is insulated.
i like to let my cat in there occasionally so she can do a little patrol.

when I bought that whole area was so dusty that I threw out all the old insulation, vacuumed and added my insulation to the floor then plywood over top.
I had to cut the plywood into 2' strips to lay it in there and I painted it white just to make it easier to see in there. I found some giant old bee hives. they sort of freaked me out and I got rid of them but later thought they were sort of interesting. maybe I should have donated them to the ecology center.

[TideWater]

Well, the demo crew got in there today so I can see what I have to work with. There's a HUGE hornet's nest. Thankfully it's winter so they're not active. I guess that explains the mystery of why we've had hornets in our house for the past 10+ years - but it makes me want to rip everything else out too just in case.

It looks like there are plenty of those foam baffles-one between each rafter-up to where the ceiling was. The ceiling might've been insulated but all that's gone now so I can't tell. My guess is that this was always a finished room with an uninsulated attic above, rather than a change made during the last renovation, because I can see marks on the old timbers from plaster lathe and the posts for the knee walls match the original materials. Below are a few photos.

One big surprise is that the air ducts are all well insulated. The only parts that aren't are the last few inches where the duct meets the vent. I wonder if that was the source of the moisture and mold?---condensation forming on that part? I have been monitoring the humidity. It was over 70% when I started but I opened the doors to the knee walls and it went down. I wonder if the high humidity was due to moisture trapped in the fiberglass?

Any thoughts about what to do while all this is open? As mentioned, the original plan is to re-insulate with Rockwool and add a hatch in the new drywall ceiling so I can inspect the attic as needed. I'm also having the soffit vents replaced but no other venting installed so I don't harm the roof--that's for another year. I can see daylight where the siding meets the chimney, so that'll need to be sealed somehow. While it's probably good ventilation, it's not weather protected so rain could blow in.

I love the old timber frame construction. I wish I could leave all this open.