New Modular Questions

[Dennisfly]

I'm placing a modular in the mountains of the west part of Virginia as a part-time residence on 29 acres. It will be 38' X 28' (two 14 foot modules) in a chalet style. That's 2 bedrooms, 1 bath, mud room, kitchen, living and dining room on the main level. There will be a large loft master bedroom and another bath which adds about 480 sq. ft. I bought the modules without the kitchen cabinets, counter tops, and flooring, as I can get better selection and prices subcontracting after the fact. The main floor will be 90% finished aside from the kitchen. The trusses and floor for the loft will be in but it will be up to me to finish that level. The foundation is cast concrete and the slope allows for a walkout style basement with 8'8'' under the floor joists which will serve as a garage and storage area. I'm serving as the general contractor and have already cleared the building area, excavated, and poured the foundation, foundation floor, and the septic system is installed. All of this work was subcontracted. The well will be drilled soon and the modules are scheduled to be delivered on Oct 1, and set on Oct 2. I'll do some of the work myself but also subcontract a lot of it.

First question for the experts on TBN: The basement has cast concrete 8" walls. The plans call for main floor insulation of R-19. The floor joists are 2 X 10 and since the basement will be a garage, the basement ceiling will have to have to be covered with 5/8 fire resistant dry wall. My inclination is to just put R-19 batts between the joists with the batt paper backing up toward the main floor. Or, should I not insulate the floor but instead insulate the basement wall? The basement is not heated. All comments and suggestions are welcome.

 

[Rustyiron]

I'd insulate the floor for sure. Can't do it after the drywall is up (for inspections/occupancy) and the walls could be done at a later date if so desired. The floor insulation will keep the cold out of your living space much better than doing the basement walls alone. A lot of your plumbing will be in that floor as well, keep this in mind when considering your insulation "package" and budget particularly in a part time home. Draining down a house in the winter is not that big of a deal if you make some simple provisions for it when you build.

 

[farmer2009]

Did you get the floor of the trailer uninsulated? Most come with a r-19 or more in the floor above the metal frame. With a backing to help with moisture.

 

[Dennisfly]

I'd insulate the floor for sure. Can't do it after the drywall is up (for inspections/occupancy) and the walls could be done at a later date if so desired. The floor insulation will keep the cold out of your living space much better than doing the basement walls alone. A lot of your plumbing will be in that floor as well, keep this in mind when considering your insulation "package" and budget particularly in a part time home. Draining down a house in the winter is not that big of a deal if you make some simple provisions for it when you build.

Thanks Rustyiron. I was thinking that way and now you have confirmed it.

 

[Dennisfly]

Did you get the floor of the trailer uninsulated? Most come with a r-19 or more in the floor above the metal frame. With a backing to help with moisture.

Thanks Farmer. It is a modular which is different from a trailer or mobile home. It has 2 X 10 wood floor joists on 16" centers with a double 2 X 10 rim and no metal. The ceiling comes with R-38 and the walls are R-21 but the floor is left uninsulated until plumbing is hooked up and the electrical circuits for the basement/garage are run

 

[woodlandfarms]

Can you provide more info on the modular you went with?

 

[wawajake]

I helped my daughter last year get her modular home finished. It was a similar situation as yours where here husband wanted to handle getting the house completed with subtrades that he arranged for the electrical , plumbing and heating and we handled the flooring and insulation decks and siding

One of the most difficult parts of the insulation aspect was the insulatiing and vapour barrier of the floor joists where they meet the rim joist board all around the outside edge of the house. Now he was doing a insulated basement, but it should be noted that this rimboard floor joist location is very busy in a modular home, with much of the electrical and plumbing coming down there.....so even if you are not insulating the basement , you will still need to do this area if your are insulating the floor. ...and that includes a vapour barrier .............and that is very hard to do in that outside rim edge location all around your house. We attempted to do the fiberglass insulation and then tape in the plastic , but getting the plastic around all the wires and plumbing etc became a nightmare of cut and paste and not a very air vapour tight.
So we found a foam spray insulation company to spray those voids ($400) and the foam is its own vapour barrier...the rest of the floor (for sound) and walls we could insulate as we saw fit later.............now of note the spray foam was not fire retardent so our bulding inspector required that a thin coat of cement grout type material be sprayed over top ($200) ...but that is probably just our Ontario building code. the picture shows the easy side of the rim joist (but we added plumbing for water heat, the other side was crazy but I did not have pic)

 

[farmer2009]

Thanks Farmer. It is a modular which is different from a trailer or mobile home. It has 2 X 10 wood floor joists on 16" centers with a double 2 X 10 rim and no metal. The ceiling comes with R-38 and the walls are R-21 but the floor is left uninsulated until plumbing is hooked up and the electrical circuits for the basement/garage are run

Sorry about that. Around here mobile and modular are used interchangeable sometimes. But I would want my floor insulated.

 

[Dennisfly]

Can you provide more info on the modular you went with?

Woodlandfarms,

We went with Express Modular. They have a web site and a Facebook page if you are interested. There are a number of modular manufacturers around the country but you apparently cannot deal directly with them. Express and other dealers use a number of different manufacturers depending on design, geographic area, price, etc. My modules are coming from Excel homes of Virginia, Mod U Kraf factory in Rocky Mount, VA. If you go direct to the factory they will refer you to an authorized dealer. They have canned plans but you can modify them as you see fit, within certain limits. You can choose stud spacing and size and select siding, windows, roofing, flooring, cabinets, and add or subtract dormers, rooms, etc.

I came to the dealer with a basic plan and they helped me modify it and chose options and design features - so mine is one of a kind. The dealer representative was very knowledgeable and helpful with design suggestions.

 

[Dennisfly]

I helped my daughter last year get her modular home finished. It was a similar situation as yours where here husband wanted to handle getting the house completed with subtrades that he arranged for the electrical , plumbing and heating and we handled the flooring and insulation decks and siding

One of the most difficult parts of the insulation aspect was the insulatiing and vapour barrier of the floor joists where they meet the rim joist board all around the outside edge of the house. Now he was doing a insulated basement, but it should be noted that this rimboard floor joist location is very busy in a modular home, with much of the electrical and plumbing coming down there.....so even if you are not insulating the basement , you will still need to do this area if your are insulating the floor. ...and that includes a vapour barrier .............and that is very hard to do in that outside rim edge location all around your house. We attempted to do the fiberglass insulation and then tape in the plastic , but getting the plastic around all the wires and plumbing etc became a nightmare of cut and paste and not a very air vapour tight.
So we found a foam spray insulation company to spray those voids ($400) and the foam is its own vapour barrier...the rest of the floor (for sound) and walls we could insulate as we saw fit later.............now of note the spray foam was not fire retardent so our bulding inspector required that a thin coat of cement grout type material be sprayed over top ($200) ...but that is probably just our Ontario building code. the picture shows the easy side of the rim joist (but we added plumbing for water heat, the other side was crazy but I did not have pic)

Wawajake,

Good idea about using spray foam in the hard to get to areas. I'll remember that. Your picture looks like you have a lowered ceiling. Did I see that correctly? I just plan to attach the drywall directly to the bottom of the floor joists for the required fire barrier.