Upgrading insulation in a home?

[rookie7]

After having to replace both hvac units for my home back in December, I am now in the process of research to seal and improve my home's insulation over the next few to several months.

My intention is to complete as much as I can. I am in the Georgia, so we have high humidity more than we don't and wide temperature swings.

My crawl space already has a vapor barrier, but it is compromised in spots. I plan to clean it up and lay down a new layer on top of existing layer, install rigid foam board on the walls per code, and close and seal off the vents. Once all that is finished my goal is to install a dehumidifier under the house. I have 2 tank water heaters, air handler, and duct work under the house.

I have 2 attics and both have full size insulated walk in doors. Part of the attic is floored with insulation underneath which is blown in fiber in some spots (not floored) and traditional batts in others.

My roof is a steep pitch due to cathedral ceilings in the home. I have researched spray foam on the rafters, but honestly that is probably going to be more than I want to spend because I don't intend to be here forever (maybe 10 years more). I'm guessing from what I have read and talked to others for me to hire a spray foam pro it would be $15K to $20K.

Any thoughts or does anyone have a home with rigid foam board attached to the rafters? I'm looking at going across the rafters not between - seems like that air pocket would be a benefit. My house has ridge and gable vents (small). I would seal up the small gable vents if I install the foam board. My other plan is to move the isulation between the joists and seal the seams etc. with foam.

I've searched and watched several videos, but would like to hear directly from home owners that have paid or done this themselves.
thank you

 

[DarnYankeeUSMC]

I would not seal off ventilation for the crawl space unless you have it done by a professional company. They use a very thick rubber like system that completely seals the crawl space. Plastic alone will not do that.

 

[Ruff 364]

Not sure if it's applicable in your situation but we just built a new home and used spray foam insulation in the exterior walls and under the roof decking. Exterior walls are 2x6's.

It gets super hot here, above 115 in the summer and we have humidity from the monsoons and the gulf of Mexico. In the summer I shot a temp gun up through the attic accesses and the interior attic temps were the same as the air temp. (House was just past sheetrock stage and no hvac) No heat being radiated into the ceiling from the attic.

It's amazing how quiet the house is too. I believe our AC/electric use will not be that much either but we aren't in the house just yet.

 

[tomcatmv]

So are your water heaters and AHU in the crawl space and are they gas or all electric?
I would not close off vents, they're there for a reason.
I'm a retired HVAC engineer/contractor. If you are at all tech savvy, you can go the ASHRAE's website and get all the info you need.
Adding insulation is usually always a good idea but you need to be careful about not "trapping" moisture i.e. high humidity because it can cause mold growth and other bad ju ju things.
I would advise you to get a couple of reputable insulation contractors to give you recommendations and bids. Spry foam is great but MUST be done correctly and is usually not good for retro fit.

 

[rookie7]

@tomcatmv my home is all electric.

 

[BuildingConceptsllc]

If ya encapsulate properly, put in a dedicated dehu for the crawl and don't exchange air. Been doing this for a long time in AL. A foamed attic humidity can be dealt with by way of the hvac system just putting a little air in it most of the time.

 

[Major Wader]

Spray foam may be less than you think, and will be the biggest benefit per $ spent.

Those guys are not immune to the attraction of cash, either. I got about 20% off my bid when I offered cash payment

 

[Alpine 338]

As Tomcat and others have suggested. Another thing to look into is having a ventilation system that draws damp air from your crawl space to the outside. Low CFM fan which can be on a timer, and will use minimal electricity.

 

[BuildingConceptsllc]

Doing this in the deep south is not like other places. You can seriously cause yourself some issues. If you do it, do it correctly with the correct components and materials. There's many encapsulation materials out there that will later make your crawl space smell like cat piss. Doing it correctly isn't cheap nor easy btw. Don't take bad advice from good intentioned home owners.

 

[redhooker]

Here’s the issue with spray foam and having an unvented attic. Especially in humid areas. The home will self destruct in the absence of electricity (unvented attics REQUIRE air conditioning underneath constantly). Many homes in Florida that either went without power due to hurricane or foreclosure filled up with black mold. Most had to be stripped to the framing to repair. A vented attic is self-drying without power so for our off-grid ready home an unvented attic would have been a horrible choice.

Conventional insulation systems use the heat of the sun to pull air up through your gable vents and out your ridge or off-ridge roof vents. Batt insulation allows moisture to pass through and evaporate. We went with a metal roof and that alone dropped our attic temp almost 30° during the summer vs asphalt shingles.

Spray foam has it’s place but it has importance drawbacks that most do not understand. Homes in Florida developed mold within just a few weeks in the absence of power.

 

[rookie7]

My plan is to tackle the attic first before it gets too hot. Crawl space can wait until summer.

I don’t plan to seel off the attic. I have vented soffit all the way around and a ridge vent on every ridge.

 

[BuildingConceptsllc]

Here’s the issue with spray foam and having an unvented attic. Especially in humid areas. The home will self destruct in the absence of electricity (unvented attics REQUIRE air conditioning underneath constantly). Many homes in Florida that either went without power due to hurricane or foreclosure filled up with black mold. Most had to be stripped to the framing to repair. A vented attic is self-drying without power so for our off-grid ready home an unvented attic would have been a horrible choice.

Conventional insulation systems use the heat of the sun to pull air up through your gable vents and out your ridge or off-ridge roof vents. Batt insulation allows moisture to pass through and evaporate. We went with a metal roof and that alone dropped our attic temp almost 30° during the summer vs asphalt shingles.

Spray foam has it’s place but it has importance drawbacks that most do not understand. Homes in Florida developed mold within just a few weeks in the absence of power.

This is correct and and there's much more as well. That's why just going and doing this or that is a bad idea. We've learned these things in the building industry over the last 20 years and there's a lot to it with humidity and the overall of how the house works, type of house, climate, ect....

 

[powell]

I put Attic foil on the bottom side of my rafters. Makes a noticeable difference in the attic space. They recommend installing a couple different ways depending on area too. Relatively inexpensive and easy to do yourself.

 

[Maggot]

I would not seal off ventilation for the crawl space unless you have it done by a professional company. They use a very thick rubber like system that completely seals the crawl space. Plastic alone will not do that.

Sealing the vents can lead to mold. Ask me how I know.

 

[rookie7]

Sealing the vents can lead to mold. Ask me how I know.

What happened? Also, if you didn’t close your vents how are you insulating under your floor and keeping moisture to a minimum?

 

[rookie7]

This is correct and and there's much more as well. That's why just going and doing this or that is a bad idea. We've learned these things in the building industry over the last 20 years and there's a lot to it with humidity and the overall of how the house works, type of house, climate, ect....

I’m doing research now and haven’t done anything yet.

 

[Devildog]

If you do choose to use foam I’d recommend closed cell over open cell.

 

[34vld]

Before you insulate, go buy the duct seal tape. It's like tinfoil with a sticky side. Seal every joint in your duct work for the cold air and forced sides. You would be surprised how much air doesn't go where it belongs until you do this. I have no insulation experience for you. Sorry

 

[BuildingConceptsllc]

I’m doing research now and haven’t done anything yet.

Cool. There's some decent info out there now but it's very hard to find enough for your specific situation and make sense of it. I'd be happy to talk to you on the phone when you are ready if you want to. It's really a house by house thing because it depends on how the house was set up, where it is, and what you want to do. We have seen foamed houses with 2 year old hvac units completely rusted and corroded out because of excess humidity as well as mold issues ect. The foam installers really don't know the whole system and what happens long term with various situations and conditions.

 

[acudaowner]

 

[Lightning8]

Georgia native and resident - lived Savannah, Warner Robins, Canton. Just bought retirement home near Milledgeville (middle GA). Attic is spray foamed in new house - amazing how cool in Summer and high temps our main issue. I have a new prefab metal storage building and had it spray foamed - it stays moderate temp year round.

 

[oneshot86]

Georgia native and resident - lived Savannah, Warner Robins, Canton. Just bought retirement home near Milledgeville (middle GA). Attic is spray foamed in new house - amazing how cool in Summer and high temps our main issue. I have a new prefab metal storage building and had it spray foamed - it stays moderate temp year round.

Take a pic of that for me

 

[Devildog]

Take a pic of that for me

House I built for a client. House was built with ICF and we foamed the back of the roof deck. It’s ideal but expensive to do.

 

[Maggot]

What happened? Also, if you didn’t close your vents how are you insulating under your floor and keeping moisture to a minimum?

I closed mine thinking it would stabilize the temperature. It did that but it also allowed mold to grow. Cost me $3000 to get it repaired at closing.

 

[ColinNSX]

As mentioned a few times, be sure to maintain air flow.

My current home is 1989 tract home in Maryland. Humid summers, cold winters. Colonial style with black shingle roof and 2x4 walls, three floors (basement, main, upstairs). Built to the absolute minimum standards of 1989.I bought the house with a high end 2-speed Lennox, 2 tons at low speed and 3 tons at full speed via a slide valve in the compressor. It worked all three tons in the summer to maintain setpoint during the summer, especially upstairs. Being hot upstairs was normal. But I didn't like that.

I had the 4" of fiberglass batts removed from teh attirc which showed the hundreds of holes that air was leaking through, and had 3" nominal closed cell foam sprayed into it's place between the truss chords which are the top side of the upstairs drywall ceiling. This immediately had a massive impact by stopping air flow through the ceiling. However, the hvac was now oversized and never jumped to the 3 ton rating which caused a shortage of runtime and subsequent shortage of dehumidication. I counter acted that by reducing the indoor blower speed. I pulled a data log watching the full summer of 2022 and the 2nd stage of A/C came on for less than five hours all summer and that was only during nightime setbacks to take the house from 73 to 70 for sleeping. It's clear that my 2/3 ton system is oversized now in A/C mode.

My next step is adding 11" of sprayed in cellulose in the attic on top of the closed cell foam. This will take me up to R60 and I'll be done up there. The attic is fully vented with soffit, ridge, and vents at the side peaks.

The next steps on this house really are to rip out sheetrock and spray the wall cavities with closed cell foam. And replace the windows as the current ~2012 units are mediocre with a poor installation. I can feel cold leaking past them in the master bedroom, I suspect no foam was used to seal the gap in the shim space.

All the above to say this:: Closed cell foam is great. However, it needs to factor into the homes climate, existing construction style, and your current HVAC. House systems are very interactive and intertwined with each other. You need to take a deep look at the entire home as a machine. Changing one major part could have an unintended consequence to another system.

 

[lightman]

After having to replace both hvac units for my home back in December, I am now in the process of research to seal and improve my home's insulation over the next few to several months.

My intention is to complete as much as I can. I am in the Georgia, so we have high humidity more than we don't and wide temperature swings.

My crawl space already has a vapor barrier, but it is compromised in spots. I plan to clean it up and lay down a new layer on top of existing layer, install rigid foam board on the walls per code, and close and seal off the vents. Once all that is finished my goal is to install a dehumidifier under the house. I have 2 tank water heaters, air handler, and duct work under the house.

I have 2 attics and both have full size insulated walk in doors. Part of the attic is floored with insulation underneath which is blown in fiber in some spots (not floored) and traditional batts in others.

My roof is a steep pitch due to cathedral ceilings in the home. I have researched spray foam on the rafters, but honestly that is probably going to be more than I want to spend because I don't intend to be here forever (maybe 10 years more). I'm guessing from what I have read and talked to others for me to hire a spray foam pro it would be $15K to $20K.

Any thoughts or does anyone have a home with rigid foam board attached to the rafters? I'm looking at going across the rafters not between - seems like that air pocket would be a benefit. My house has ridge and gable vents (small). I would seal up the small gable vents if I install the foam board. My other plan is to move the isulation between the joists and seal the seams etc. with foam.

I've searched and watched several videos, but would like to hear directly from home owners that have paid or done this themselves.
thank you

Just a suggestion. Talk to your electric supplier. Many of them offer things like free home inspections where they recommend improvements, grants or other type of assistance for insulation, or sometimes interest free financing for energy saving improvements.

 

[rookie7]

@ColinNSX most of my attic is flooded with plywood for storage. I have considered moving stuff around and taking out the fiberglass batts and spray foam on top of the sheet rock then put the floor back down.

 

[ColinNSX]

@ColinNSX most of my attic is flooded with plywood for storage. I have considered moving stuff around and taking out the fiberglass batts and spray foam on top of the sheet rock then put the floor back down.

I had to rip up the 5' wide path of 2x6 boards that went end to end. But it was worth it with the increased comfort upstairs. I don't use the attic for any storage.

 

[redhooker]

@ColinNSX most of my attic is flooded with plywood for storage. I have considered moving stuff around and taking out the fiberglass batts and spray foam on top of the sheet rock then put the floor back down.

I have never seen foam installed over the ceiling, only to the underside of the roof deck.

Airflow does not need to be maintained in an unvented attic (this is the term for most foam applications). The attic is sealed, and yes it does cost less to cool the home, about 10-25% less depending on the other insulated surfaces and windows (cmu is usually the lowest r rating, ICF the highest). Usually count on about 75% of whatever they tell you the savings will be. I have had the advantage of seeing identical homes side by side, one foamed and one conventionally insulated. The foam house actually cost about the same to cool, but was running a smaller tonnage system that ran more frequently. Another interesting observation was the foam house had a light silver shingle and the batt had black. These were model homes and not lived in so an ideal comparison. You have to remember as well, with an unvented attic you are actually cooling and heating the attic as well as the living space.

The issue I raised earlier, is retrofitting an older home is problematic because spraying foam in your attic is part of the system and you need to ensure you address everything else. While batt can be used in the walls the vapor barrier needs to be sufficient, and in older homes this is rarely the case.

Also you need to be confident you will have continuous access to grid supplied power for the life of the home. We designed our home to be as comfortable as possible without HVAC in the event the grid becomes undependable (this scenario seems more possible every passing year). We have a large solar array (60 330w panels) and a 22kw generator but still want our home to be capable of surviving a no power situation.

We have cross ventilation in every room and situated the home to take advantage of the sunlight throughout the year, the lower path in winter shines further into our main living areas, the covered front porch is deep enough it shades the entire front wall in summer.

Good luck solving these issues I would take advantage of the earlier post offering a consult on the phone. Have as many insulators come out and get a variety of opinions. Unfortunately not a single one offered me the correct advice for what we needed, none mentioned the mold issue with no AC. We had to find this out on our own.

 

[Major Wader]

We used open cell foam for all insulation. No attic, upstairs room ceiling nailed to the rafters and wind girder.

A/C in the summer, heat and dehumidifiers in the winter. Backup generator runs whole house in power outage.

 

[HeavyAssault]

All this talk about insulation....yet nothing about using quality windows. Put 15" thick walls up and all the insulation you want....then cut a hole in the wall to install some cheap ass window. Yea you will loose heat or cooling air.

I can tell you the single biggest thing I've noticed in various home were the windows are/can be the WORST spot for heat transfer. I'll be building a new home in the relative near future...triple pane windows will be used while not wasting money either.

 

[338dude]

After having to replace both hvac units for my home back in December, I am now in the process of research to seal and improve my home's insulation over the next few to several months.

My intention is to complete as much as I can. I am in the Georgia, so we have high humidity more than we don't and wide temperature swings.

My crawl space already has a vapor barrier, but it is compromised in spots. I plan to clean it up and lay down a new layer on top of existing layer, install rigid foam board on the walls per code, and close and seal off the vents. Once all that is finished my goal is to install a dehumidifier under the house. I have 2 tank water heaters, air handler, and duct work under the house.

I have 2 attics and both have full size insulated walk in doors. Part of the attic is floored with insulation underneath which is blown in fiber in some spots (not floored) and traditional batts in others.

My roof is a steep pitch due to cathedral ceilings in the home. I have researched spray foam on the rafters, but honestly that is probably going to be more than I want to spend because I don't intend to be here forever (maybe 10 years more). I'm guessing from what I have read and talked to others for me to hire a spray foam pro it would be $15K to $20K.

Any thoughts or does anyone have a home with rigid foam board attached to the rafters? I'm looking at going across the rafters not between - seems like that air pocket would be a benefit. My house has ridge and gable vents (small). I would seal up the small gable vents if I install the foam board. My other plan is to move the isulation between the joists and seal the seams etc. with foam.

I've searched and watched several videos, but would like to hear directly from home owners that have paid or done this themselves.
thank you

Anything would help but with rigid foam board unless you’re going to go something like 2 inch thick you’re only getting 3 to 5 R’s it’s not worth the expense