I've never done this before and plan to just pay someone to come do it. House built in the late 70s.

Plan is to remove all the old because rodents/bats/wtf ever lived up there. What else do I need to know?

AlaskanAg99 said:

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I've never done this before and plan to just pay someone to come do it. House built in the late 70s.

Plan is to remove all the old because rodents/bats/wtf ever lived up there. What else do I need to know?

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Easy time to have a plumber come inspect all pipes up there after they have removed the old but before they blow in new. Especially if you are running old galvanized piping. Have him plan to fix after blow in (mark spots with flags higher than blow in etc) or during it if the contractors can play nice together. Ask for pex for any replacements done.

FatZilla said:

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AlaskanAg99 said:

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I've never done this before and plan to just pay someone to come do it. House built in the late 70s.

Plan is to remove all the old because rodents/bats/wtf ever lived up there. What else do I need to know?

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Easy time to have a plumber come inspect all pipes up there after they have removed the old but before they blow in new. Especially if you are running old galvanized piping. Have him plan to fix after blow in (mark spots with flags higher than blow in etc) or during it if the contractors can play nice together. Ask for pex for any replacements done.

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We replaced with Pex a decade ago.
Although may have another person go up to re-route some lines, install a manifold, possibly a filter for the waterheater.

Might have someone check all your eaves without the blown in to see if any of them need repair/unblocked. Those are the only 2 i can think of where the insulation can block easy inspection.

Assuming you have soffit/ridge venting, have soffit baffles installed before new goes in. Hopefully that's included in the contract. Otherwise your ventilation flow will be destroyed.

How deep are you getting it blown in? Might as well go R-60 if possible. The marginal cost of additional depth over R-38 should have a good ROI.

We have plus down in some areas for storage. Should that be pulled up and closed cell insulation installed before putting thr ply back down?

Hood idea on the vents, I'll make sure that's part of the contract.

We had this done. There were 2 options (maybe more sub-types) of the new insulation. One was supposedly somehow supposedly disagreeable to rats/mice, so that may be something to consider.

Unfortunately, our installer somehow forgot that we requested that insulation and installed the other.

We prefer Rockwool
Time to seal flues & ducts

AlaskanAg99 said:

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We have plus down in some areas for storage. Should that be pulled up and closed cell insulation installed before putting thr ply back down?

Hood idea on the vents, I'll make sure that's part of the contract.

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Make sure each that requires it is wired to a proper junction box while its all uncovered too for sealing. Will save you lots of hassle and headaches later trying to get it up to code if ever need to sell. Have them mark the wire run to the nearest joist with a staking flag or similar if you need electrician to come out after to install boxes.

Somewhat related question

Once you have new insulation blown in, does that pretty much preclude you using the attic for storage of things like holiday decorations, etc? Given that your ceiling joists are likely 2x6, going back with 12"+ of insulation obviously buries all of them, so trying to go back with any sort of walkway or decking would either require you to build it up on risers (doable, but effort and cost) or smash down the insulation (defeating the entire purpose).

We have 3 different attic sections on our current house, and each one has a different degree of insulation based on how much that part of the house has been remodeled, ranging from little to none over the kitchen (re-done) to a good amount over the master bedroom. I'd like to be able to use all 3 for varying degrees of storage, but I'm trying to determine if I need to do a lot of building in those spaces first to get all the decking and storage platforms in place before calling the insulation guys.

Or would it be easier to just spray foam at the roof level and remove all cellulose/batt insulation?

This was my question as well as we have decking down for storage. My idea was to pull up all the decking and spray in closed cell expanding insulation and then cut it down to even with the supports, the reinstall the decking.

We may enclose our covered patio so running a new electrical circut there is something else id have to consider and if we install a wet bar running H/C water lines nearby to be pulled down later.

Unfortunately its not just a quick remove/replace project. I can already think of 4 other things that need to happen before new insulation gets blown in.

You have to elevate your platform to get the required insulation underneath. Back when it was r 30 code and 2x6 joist you would turn another set of 2x6 perpendicular to get ~11 inches of space underneath for blown in.

I've done about half of my house, removing the old stuff and then putting on the other side of the attic. I added a 2x4 on top of my 2x6 rafters. This gave me space to put R38 and then deck on top with 1x4 furring strips.

If you're going to deck, I like the 1x4 (or 1x3) instead of plywood because it is easier to 'form' to the attic spaces (ducts, pipes, framing, etc.) and use drywall screws (3 or so per board). Use sawzall to cut the boards as needed.

Also, if you are going to deck, install more lights. I installed like 4-6 4" round boxes tied off the main single light. Put CFL's on the basic ceramic base. Put 1 or 2 ceramic plates with an outlet for random outlet in the attic as needed.

~egon

Wow, this project just keeps growing in scope. No longer a simple remove/replace insulation. This is now a Fall 2025 Attic Rehab projects. Here's my list and sort of in order:

1. Remove existing insulation.
2. Seal registers, vents, can lights, build a boxes for in-ceiling speakers
3. PEX: Re-route some lines as the plumber 10 years ago went shortest distance and this has caused other issues. Install a manifold so I can shut down water supply to outside faucets. Add a new H/C line and stub it off for future patio conversion to living space.
4. Electrical: seal/mark existing junction boxes, remove all old wiring (mostly phone lines), add a run to the master bath for a fancy lit wall mounted magnifying mirror. Run a new circuit for future bar. Install 3rd lightbar
5. build cross members for proper R values, add some sort of decking. Shore up vertical roof supports (idiots used 1"x10" and all are bowing. New roof needed in <5yrs.

Thankfully I have a list of contractors to do all of this and now there's enough for a least a days worth of work. Plumber and Electrician will do small jobs.

I've also kicked around the idea of replacing all the vent/flexible duct work in the attic since it's nearly 50 years old. Anyone else done this?

I know I've seen it discussed a few times before on here...

Given the extent of all that effort, would it be worth it to consider spray foaming the underside of the deck instead? If you're planning to replace the roof in 5 years, it may not be. But my roof is in good shape, so I'm wondering if it wouldn't be a better end product to take that approach. I know I'd have to make some modifications to gas furnace and water heater to make sure they are venting properly. But otherwise, having easy access to all the water lines, AC registers, electrical drops, etc. seems like it would be much easier, not to mention storage without having to build risers wherever I want to store things. I just know I hate getting up there and having to dig through all the insulation looking to see where I can step, where electrical lines are running, etc.

YellAg2004 said:

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I know I've seen it discussed a few times before on here...

Given the extent of all that effort, would it be worth it to consider spray foaming the underside of the deck instead? If you're planning to replace the roof in 5 years, it may not be. But my roof is in good shape, so I'm wondering if it wouldn't be a better end product to take that approach. I know I'd have to make some modifications to gas furnace and water heater to make sure they are venting properly. But otherwise, having easy access to all the water lines, AC registers, electrical drops, etc. seems like it would be much easier, not to mention storage without having to build risers wherever I want to store things. I just know I hate getting up there and having to dig through all the insulation looking to see where I can step, where electrical lines are running, etc.

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For an older home, foaming the underside of the deck is not advisable unless if a structural engineer has reviewed the design and can confirm that the roof framing can withstand the added weight of the spray foam. Additionally, adding spray foam to an attic not originally designed for it can introduce issues with ventilation/humidity, particularly if the ventilation is not modified accordingly at the same time.

hijakeroo123 said:

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YellAg2004 said:

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I know I've seen it discussed a few times before on here...

Given the extent of all that effort, would it be worth it to consider spray foaming the underside of the deck instead? If you're planning to replace the roof in 5 years, it may not be. But my roof is in good shape, so I'm wondering if it wouldn't be a better end product to take that approach. I know I'd have to make some modifications to gas furnace and water heater to make sure they are venting properly. But otherwise, having easy access to all the water lines, AC registers, electrical drops, etc. seems like it would be much easier, not to mention storage without having to build risers wherever I want to store things. I just know I hate getting up there and having to dig through all the insulation looking to see where I can step, where electrical lines are running, etc.

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For an older home, foaming the underside of the deck is not advisable unless if a structural engineer has reviewed the design and can confirm that the roof framing can withstand the added weight of the spray foam. Additionally, adding spray foam to an attic not originally designed for it can introduce issues with ventilation/humidity, particularly if the ventilation is not modified accordingly at the same time.

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Yes, more times than not you usually create a potential mold/mildew issue because the foam causes the existing ac unit to be oversized resulting in short run times and poor humidity reduction. Also if gas furnace or water heater/tankless in the attic you will have to retrofit to get make up air to them. I have seen situations where it was beneficial such as when someone added on and the ac was fairly new but became undersized and house would not cool below ~78 in summer and ran nonstop. . After foaming the rafters/decking the house would then cool to around 72 and would actually cycle on and off. Foam has its pros but there are also cons as well.

AlaskanAg99 said:

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Wow, this project just keeps growing in scope.

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I have yet to read an explanation of how creating a double-sided vapor barrier sandwich (roof underlayment on topside of decking, closed cell foam applied to underside) doesn't lead to a rotten roof deck.