Redoing underbelly on 1973 DW
Posted: Mon Nov 09, 2015 11:59 pm
Hi everyone, I am going to be redoing the underbelly myself on my 1973 double wide after a furnace company replaces the two tracks with galvanized sheet metal this friday. This is in northern Michigan, so I have to do all this fast as I can at this time in the year. Got a quote of $4200 to redo underbelly and reinsulate with just r-13 from the only ones that do it in this area, yeah just nuts, alot of elderly people live here and thats what they do for them.
Anyhow, right now what is down there is about 3in of insulation stuck to the back of the I am guessing original belly board, this does next to nothing and floors are very cold in winter, it is like cardboard, with a thin black layer on either side about 1/8" thick, no insulation for a good 2 feet out from the rim joists, It is stapled along rim, and to the floor joists, but the staples are a good 6" form each other allowing cold air to get into the belly along the rim in wind, as the wrap hangs alittle between staples. The wrap is fed under all the steal I beams and hangs down with the insulation a good foot from the bottom of the floor joists, I rough measured 5 1/2'' thickness for the floor joists that I could get insulation in, this might be off a bit, it was through a hole.
The furnace tracks sit below the floor joists, so there is a good gap to the floor, cardboard whatever covers about 1/4'' thick under tracks with no insulation.
I plan to tear out old wrap and insulation along both furnace tracks about 6 1/2' wide I beam to I beam for duct install, and at that point there is only about 30in of old on the front and the back of the place to replace and insulate, and another 6 1/2' right in middle of the place, so I am going to get those out too, and will be putting down the 6mil black vapor barrier on the ground once complete and wont get torn, but have now run into two different methods of doing the belly, and have alot of questions.
1. r-19 unfaced held into joist spaces against floor(particle board) with wire, 16x80 "mobile flex" product to be cut and used as wrap, stapled and glued at rim, fed under I beams, stapled at all joists, flex mend tape for any tears during install.
Now, someone told me this way the pipes can freeze? they are copper piping throughout place, most along tracks, did not freeze during last winter without furnace running at all, some guy tells me that is because there was an air pocket under whole place, and air could move? this does not make scene to me as it would be below freezing air. Heat tape is on main supply line about 4 feet just ground to wrap.
The rest I just had 3 space heaters going in living space$$$$$$$ as I had no money for duct, UB replacement last year. I guess the concern here is compressing the pipes with insulation in spots where it is not along the tracks? if so should one leave a gap for the lines above the insulation a few inches in those areas?
I would really prefer to do it this way with insulation between joists, but not if it will cause problems.
2 r-19 or above faced, and glued to same or different wrap, and nothing in joists, this would allow the "gap" between the insulation and joists, floorboards and some air to cycle around, but my floors would be colder.
What type of wrap is best to use, it looks like the flex mend mobile flex bottom board is the only one I can find for sale online, is it the right stuff for what I want to do? would it work with method 2 if needed? (weight support of insulation).
A local guy uses house wrap for all ub replacements, says its the only product that will breath and not trap moisture, and to use that in place of mobile flex, with the unfaced r-19 in floor joists?
Will the fiberglass r-19 be the best option if done in joists, I got about 5 1/2''-6'' thickness for joists, don't want to compress, but r-13 is too low. If it "hung" down a few inches from the floor joists would that be a problem if it was not compressed and held up well? I had planned r-30 for this. or is another type of insulation that mold can not grow on a better option for ~6in?
What would be a good insulation to place under the new metal furnace tracks? can I use r-13?
This is all the questions in my head for now,
thank you for taking the time to read.
Anyhow, right now what is down there is about 3in of insulation stuck to the back of the I am guessing original belly board, this does next to nothing and floors are very cold in winter, it is like cardboard, with a thin black layer on either side about 1/8" thick, no insulation for a good 2 feet out from the rim joists, It is stapled along rim, and to the floor joists, but the staples are a good 6" form each other allowing cold air to get into the belly along the rim in wind, as the wrap hangs alittle between staples. The wrap is fed under all the steal I beams and hangs down with the insulation a good foot from the bottom of the floor joists, I rough measured 5 1/2'' thickness for the floor joists that I could get insulation in, this might be off a bit, it was through a hole.
The furnace tracks sit below the floor joists, so there is a good gap to the floor, cardboard whatever covers about 1/4'' thick under tracks with no insulation.
I plan to tear out old wrap and insulation along both furnace tracks about 6 1/2' wide I beam to I beam for duct install, and at that point there is only about 30in of old on the front and the back of the place to replace and insulate, and another 6 1/2' right in middle of the place, so I am going to get those out too, and will be putting down the 6mil black vapor barrier on the ground once complete and wont get torn, but have now run into two different methods of doing the belly, and have alot of questions.
1. r-19 unfaced held into joist spaces against floor(particle board) with wire, 16x80 "mobile flex" product to be cut and used as wrap, stapled and glued at rim, fed under I beams, stapled at all joists, flex mend tape for any tears during install.
Now, someone told me this way the pipes can freeze? they are copper piping throughout place, most along tracks, did not freeze during last winter without furnace running at all, some guy tells me that is because there was an air pocket under whole place, and air could move? this does not make scene to me as it would be below freezing air. Heat tape is on main supply line about 4 feet just ground to wrap.
The rest I just had 3 space heaters going in living space$$$$$$$ as I had no money for duct, UB replacement last year. I guess the concern here is compressing the pipes with insulation in spots where it is not along the tracks? if so should one leave a gap for the lines above the insulation a few inches in those areas?
I would really prefer to do it this way with insulation between joists, but not if it will cause problems.
2 r-19 or above faced, and glued to same or different wrap, and nothing in joists, this would allow the "gap" between the insulation and joists, floorboards and some air to cycle around, but my floors would be colder.
What type of wrap is best to use, it looks like the flex mend mobile flex bottom board is the only one I can find for sale online, is it the right stuff for what I want to do? would it work with method 2 if needed? (weight support of insulation).
A local guy uses house wrap for all ub replacements, says its the only product that will breath and not trap moisture, and to use that in place of mobile flex, with the unfaced r-19 in floor joists?
Will the fiberglass r-19 be the best option if done in joists, I got about 5 1/2''-6'' thickness for joists, don't want to compress, but r-13 is too low. If it "hung" down a few inches from the floor joists would that be a problem if it was not compressed and held up well? I had planned r-30 for this. or is another type of insulation that mold can not grow on a better option for ~6in?
What would be a good insulation to place under the new metal furnace tracks? can I use r-13?
This is all the questions in my head for now,
thank you for taking the time to read.