Old House Reno....Insulation Issue

older houses like that were built before AC and thus are designed to breathe. You’re gonna be chasing air but you can still get a decent amount of conditioning. So yes I would spend my money at the roof and the floor.

My house is 50 years old, the biggest improvement we’ve been able to make was new doors and windows and a new more efficient set of equipment.

I'd like to change the windows, but i find it will take away from the charm of this particular house so i'll probably reglass them.

I mentioned this issue to an HVAC guy and he wasn't alarmed by the possibility losing air or the house breathing. Seemed pretty common and is addressed by more efficient units or slightly upsizing the unit.

Same issues. 100year old house, been in it about 10 years. The exterior is cypress/cedar lap siding without sheathing. I have old tar paper as the "weather barrier" which I'm sure is gone at this point. Previous Owner did blown insulation in stud cavities, which has probably settled a good bit over time. I've added 2" closed cell spray foam 4 years ago and just added more blown insulation in attic over existing insulation.

Original windows, which do leak. I've accepted the fate that the more I do, likely the worse I make the house in that it was built to breathe.

I'd think the tyvek is OK and recommend the closed cell spray foam below and blown insulation in attic.

Yep! My first little 1500 sq ft raised house was ~90 years old which did have central a/c installed ~15 years prior. After moving into it in the fall I instantly noticed how dam cold it was. Zero insulation! Crawling under that sob to wrap pipes was a biotch and was a one and done job! After that I had it sprayed with open cell which helped dramatically. I then followed that up with some blown in insulation all over the attic area. Last thing I did was replace those old foggy windows with the weight where moisture and mildew was a constant problem of cleaning. Lived there for 15+ years and was a overall great house till we had out grown it.

There is recent thread, on page 2, of a poster who recently moved in a historic (100+ years) on the MS Gulf Coast dealing with a few issues related to HVAC & insulation - you should read the thread LINK

Most heat gain and loss for a majority of homes is through the attic, floors (elevated homes) and windows - windows are a much greater source of heat loss & gain than many realize, for my house 40%, and I would say my house is not window “heavy”, just “normal”, and I have double pane windows. Read this before you insulate your floors Insulating Raised Floors in Hot, Humid Climates LSU AgCentet

You need to calculate heat gain & loss for the house, considering the energy-insulation improvements you make, to properly size the HVAC system. You’d better run from any HVAC contractor that sizes your HVAC on a 1 ton of HVAC per 500 sq ft “rule of thumb”, particularly for a 100 year old house, without taking into consideration is age and the energy improvements you plan to make.

Heat loss & gain, and HVAC sizing is properly done via a manual J calculation. Professionals do this, not terribly expensive, $350-500, depending on the size of the house. Here is a free online manual J whole house calculator that you you can use, and you can play around with it to determine how insulation and window improvements will affect your heat load. Load Calc.

A blower door test, air filtration test, should be done to determine the amount and locations of air filtration - in your case before (help with finding & fixing major sources of air gain & loss) and after you make your improvements as this is usually a major component of the manual J and HVAC sizing. Again, not terribly expensive, $350-500, and some utility companies have programs where they pay for it, you just have to check.

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That's a lot to digest Starting to rethink my purchase.....but not really. I'm thinking that foam underneath, blown in cellulose in attic....maybe some type of indow thermal insert for windows?? Hopefully it doesn't turn into a full blown mystery as in the other thread that you provided.

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Just don’t want you to be “penny wise, pound foolish”, easy for me to say with your money….lol. Everything you want/need to do - blown in attic insulation, foam sprayed underfloor, thermal inserts for windows - is spot on and you’ll want use that info in sizing the HVAC. Sealing all the major air entry points in the attic is way easier before adding blown-in insulation than after.

It really isn’t that complicated. But your going to be spending $1000s on insulation, window improvement and HVAC, you just want to make sure is everything is done right so you have an issue like the other poster - which hopefully he’ll get sorted out before long. One thing you don’t want to do is oversize your HVAC & undersize the ducts b/c those things cannot be easily corrected without investing more big $$$. Rarely is HVAC equipment under-sized, but over-sizing them is far to common.

If you want a good readable reference book to help you along and answer many of your questions consider buying this.

A House Needs To Breathe…Or Does It? An Introduction to Building Science by Allison Bailes, Ph.D.. $50 on Amazon.

Again very readable, even for a non-technical person. The author, with a Ph.D. in physics, is originally from south Louisiana, but has been in Atlanta for many years and he has a business that does all the things I mentioned He has an excellent blog from which I learned a lot.

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use a hole saw to create a location to blow the walls with fiberglass etc

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Certainly an excellent option for insulating, uninsulated exterior wall cavities that have no horizontal firebreak stud in the wall, and most older homes would not have that. Some are able to do it from the outside (exterior) with lap board sliding by removing the top board, blowing in the insulation and then reinstalling the removed board.

Lots of YouTube videos of both approaches.