We’re remodeling and adding an addition onto our 1940’s wood frame home. Half the existing walls are covered with the old asbestos siding the other our covered 7″ wood siding. All is to be replaced with hardi-plank.
There is no plywood on any wall of the house. If the wall has the asbestos siding there is no insulation between it and the plaster interior walls (and curently those walls are quite cold). On the walls where they have replaced the asbestos with the wood siding (rots), they put fiberglass insulation there (those walls tend no to be quite as cold right now).
I’m removing all siding and using hardi-plank.
Questions:
1) Since I am using hardi plank do/should I add OSB or plywood to the walls before the hardi-plank? What are the +/-‘s?
2) What about insulating?
I don’t won’t to say money is no object, however I don’t want to be stupid and spend senselessly. I’d like to do this part of the job right, without breaking the bank.
Thanks for all the input
Replies
when you have the siding stripped off the sheating you can drill a hole in each stud bay and blow in cellulose. The recycled newspaper is a great insulation that doesn't trap moisture like fiberglass.
After drilling the holes I like to cover the walls with felt paper, marking the stud centers as I go, this makes fastening the hardi-plank that much easier.
I may have erred in my description. There is no sheathing. Its siding and studs. Thats it.
Thats why I was wondering if I should go with OSB or plywood, in addition to the insulation. Or other options.
I've read the archives on this and other scenarios and frankly its difficult to determine which would be the "best" way to go on this. -----------------------------------------------------------------------------
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one, you have an asbestos issue to deal with, yikes
as a homeonwer you can remove it and legally dispose of it properly. as a contractor I cant touch it
sheeting question
I prefer real plywood when cost is not such an issue. For example our current project, 1/2 cdx was approx 3 dollar a sheet more then 7/16 wafer
siding nails ( shiners) that dont hit a stud but hit sheeting will hold better in plywood.
Of course you want all your nails to hit studs
I like plywood, and usually use 5/8". Fir if it's going to be exposed for awhile, SYP is fine if you'll cover it right up. My reason is plywood will greatly add to the wall's wind resistance. In fact so much so that our strict building codes allow you to forgo corner wind bracing in the frame if you use plywood panels. And I've read that if you use 2X the nails (i.e. say 10 nails instead of 5 in the 4 foot width of sheet attaching to the stud), you'll multiply the walls shear strength by 10.
Always a good idea to upgrade the insulation when you have the opportunity. What kind would be up to you and might be determined by your location.
With no structural sheathing under the current siding to impede the placement you should breeze right through the insulation once you get all that old siding material into the dumpster.
Sheathing is optional under Hardi plank. Read the directions that come with the product. You must, however, have some form of protection from the elements, such as house wrap, felt, etc. and possibly a retrofit of all flashing.
You should notice when you pull the siding that you have let-in diagonal bracing. If for some reason you do not, then sheathing is necessary. If you decide to go with ply or OSB you will most certainly have to replace all the window and door trim and may even have to have jamb extensions.
My feeling is that a flat sheathing yields a better finished product and gives more nailing options. If you apply Hardiplank directly to studs you will end up wasting more material because you will have to cut almost every piece so the ends fall on the nailing points. Hardie will also forgive a hard blow if there is continuous backing more so than if there is "give" between studs. The occasional facenail also holds better in material other than air space.
Probably you should install some sort of sheathing -- plywood, OSB, or even foamboard. You can either install fiberglass batts before the sheathing goes up, or put up the sheathing and then blow in cellulose.The main argument against sheathing (besides the expense) would be that it adds thickness that may mess up your windows a bit. An important argument for it, in FL, is that it will add significant structural integrity (in addition to helping seal the house against weather).It would be wise to put Tyvek or something similar over the sheathing before siding. (Even more important to put up the Tyvek if you don't add sheathing.)I gather you live in Tampa, FL. Farther north cellulose would be the way to go, but down there unfaced fiberglass batts are probably fine, and will allow you to do things a little more incrementally. The real benefit will come from the housewrap anyway.Probably the single most important thing is to pay careful attention to flashing around windows, etc, so that you keep water out of the walls.
please think outside the box!
For example where is your nearest small sawmill? will they sell you mill run boards at a reasonable price? then buy from them! Sure they're green so is most wood in new construction! I can buy 32 square feet of 1 inch thick boards for around 12 bucks around here. single boards are much easier to handle and nail up than a 4x8 sheet of plywood. plus it's a better nailing surface..
Then look around at quarries and other sources of local rock. I was able to buy rock for far less than the same amount of hardie board would cost. I put a simple brick (stone) ledge in and then just started to put up stone. (nope never had done it befor , but I watched masons do it for a while and it didn't really seem all that difficult. I bought a cheap electric cement mixer I'll sell when the contruction is done, lot's cheaper than rental and you won't get your undies in a bunch rushing to finish the project before the rental store closes..
I made life harder because I had to put stone around all the timbers on my timber frame. thus I was constantly fitting stone into boxes.. Still it went really easy. I could do a 4x6 square in about 3 hours and if I just had a flat wall where I didn't need to fit so much I suspect I could do about at least a 4x8 foot area in that same amount of time..
Let's see cheaper and better, what's not to like?
As for insulation, once I got the walls open I'd have someone come in and spray foam.. Better insulation, queiter and makes the house stronger, what's not to like?
Frenchy, welcome back. You were missed. How's the project?
Did you figure out how to work a camera?Remodeling Contractor just outside the Glass City.
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I would add plywood or OSB just for some rigidity and if you plan on tearing out the old interrior add something with a vapor barrier while insulating.
If this is FL then an inside vapor barrier may not be recommended.