Mounting PV on Modular homes

[toddbailey]

Does anyone know if a module home design/built in the mid 1980's can handle the additional weight imposed by Solar panels, racks, inverters etc?

I have a 48x24 mobile home with good exposure that I'd like to mount 32 panels on, 16 per side. That's 800 pounds spread out over a 324 sq ft (12x27) area or about an additional 2 1/2 pounds per sq ft, if I did the math right.

[inetdog]

Does anyone know if a module home design/built in the mid 1980's can handle the additional weight imposed by Solar panels, racks, inverters etc?

I have a 48x24 mobile home with good exposure that I'd like to mount 32 panels on, 16 per side. That's 800 pounds spread out over a 324 sq ft (12x27) area or about an additional 2 1/2 pounds per sq ft, if I did the math right.

If the modular was designed for a reasonable snow load, it should be able to handle the weight of the panels without snow.
There are some design requirements which all modulars have to meet, but beyond that it may vary by manufacturer, model and special order. Look for engineering specs from the manufacturer if you can.

[toddbailey]

Unfortuantely, I have no way of determining who originally built the home nor it's model or any other specifics.
From your comments I suppose once size doesn't fit all.

It's easy to say probably not but I need to find out for certain before planning a phase 2 install.
Hiring a structural engineer isn't an option due to their costs

Is there any other way to determine if the existing structure caould support the weight of panels plus snow?

Perhaps some knows of a web site that allows you to enter various parameters and out pops a display that shows load factors?

[inetdog]

Unfortuantely, I have no way of determining who originally built the home nor it's model or any other specifics.
From your comments I suppose once size doesn't fit all.

It's easy to say probably not but I need to find out for certain before planning a phase 2 install.
Hiring a structural engineer isn't an option due to their costs

Is there any other way to determine if the existing structure caould support the weight of panels plus snow?

Perhaps some knows of a web site that allows you to enter various parameters and out pops a display that shows load factors?

There might be, but do you have all of the necessary inputs in terms of the shapes, interconnections and sizes of the roof and wall components?
You also need to know the weight of the existing roofing materials and whether there is just one layer or if additional layers have been added.

My double-wide had a certification nameplate on the outside that did not specify a manufacturer's model number directly but could probably be referenced to a registered design on file somewhere.

[toddbailey]

There might be, but do you have all of the necessary inputs in terms of the shapes, interconnections and sizes of the roof and wall components?
You also need to know the weight of the existing roofing materials and whether there is just one layer or if additional layers have been added.

My double-wide had a certification nameplate on the outside that did not specify a manufacturer's model number directly but could probably be referenced to a registered design on file somewhere.

I found some load calculators on the web, so I'll take some measurements and see what comes up.

As it turns out I get to do a roof repair over the next few days as a section of the roof is sagging several inches from last years snow dump.
A contractor estimated their $2500 min bid for the job and I said but it's only 3 sheets of plywood, a few 1x4's, three packets of singles .
They said yup but sorry, we have a min. charge


I suppose, glad I'm handy with a saw and hammer...

[inetdog]

I found some load calculators on the web, so I'll take some measurements and see what comes up.

As it turns out I get to do a roof repair over the next few days as a section of the roof is sagging several inches from last years snow dump.
A contractor estimated their $2500 min bid for the job and I said but it's only 3 sheets of plywood, a few 1x4's, three packets of singles .
They said yup but sorry, we have a min. charge


I suppose, glad I'm handy with a saw and hammer...

Some of the posters here have recommended a way of parking the panels vertical during the winter. That way there is no snow load directly on the panels, they are not obscured by snow, and they benefit from extra light reflected off snow on the surrounding ground. Not sure if that is possible/appropriate for a roof mount, but you might want to consider it.

[toddbailey]

Some of the posters here have recommended a way of parking the panels vertical during the winter. That way there is no snow load directly on the panels, they are not obscured by snow, and they benefit from extra light reflected off snow on the surrounding ground. Not sure if that is possible/appropriate for a roof mount, but you might want to consider it.

I'm going to assume that for now the roof is designed for 20-25 psf. But once I get inside I can take measurements. We don't get a lot of snow, maybe 1 or 2 weeks a year. After all it's called rainy Seattle for a reason.
Winter in Seattle is a depressing wet or heavy overcast 4-5 months, we usually don't have sunny days until July 5th. And looking at pv watts site data there isn't much sunlight there to collect, I think that last year we got 2 weeks total of sun to partial sunny days. So long story short there isn't much to be gained in raising the panels to vertical.

In any event, panels on the house won't happen until next year anyway. After the roof is fixed, I get to resize part of the shop/carport to allow a 3x6 array with options of 3x9 or put another way expand the south roof from 12x20 to 20x20 and again to 20x30. When done I'll have 27 250 panels facing 140 degrees south at a 222 or 26 degree elevation 6750 watt.

The house with it's east/west facing roof will see the addition of 8000 watts. Which I think will keep the utility bill under control.
at least it looks good on paper

[Naptown]

worst case would be to attach the racking rails at every framing member (assuming a 24" OC rafters or trusses)
Solar panels and racking really only weigh about 3# per square foot. Most roofs in areas where they get any snow at all are usually rated for 20-25#
Realize that there is also a 15# per square foot dead load (what the rafter, plywood and shingles weigh) built into the calculation. Rarely does this actual weight exceed 8-9# PSF

[toddbailey]

worst case would be to attach the racking rails at every framing member (assuming a 24" OC rafters or trusses)
Solar panels and racking really only weigh about 3# per square foot. Most roofs in areas where they get any snow at all are usually rated for 20-25#
Realize that there is also a 15# per square foot dead load (what the rafter, plywood and shingles weigh) built into the calculation. Rarely does this actual weight exceed 8-9# PSF

So putting this another way, Am I looking for a problem that doesn't exist?

[Naptown]

So putting this another way, Am I looking for a problem that doesn't exist?

probably so actually it will be up to the Inspector to decide

[inetdog]

Realize that there is also a 15# per square foot dead load (what the rafter, plywood and shingles weigh) built into the calculation. Rarely does this actual weight exceed 8-9# PSF

The most common reason for this being exceeded, IMHO, is the addition of multiple additional layers of roofing without removing the old ones. And even that will probably not take you above the assumed dead load.
Unless, of course, somebody put a concrete tile roof on the modular.

[toddbailey]

probably so actually it will be up to the Inspector to decide

Too put an interesting spin on this project,I need a bit of everyone's legal opinion on the following:

I purchased the current residence about 10-14 years ago. A new roof was needed and as part of the deal, the seller paid for the project.
To reduce roof clutter a ridge vent was installed. During the roofing project, I took a look at how they were installed, to my dismay, the vents are blocked the entire length of the roof ridge.
So basically I paid extra for ridge vents that were improperly installed. As a possible result of the improper attic vent installation, I'm finding the plywood is delaminating and roof trusses are failing.

Does anyone think I should see if the company is still in business and file a civil suit in court to cover the costs and fix /replace the damage?

[inetdog]

Too put an interesting spin on this project,I need a bit of everyone's legal opinion on the following:

I purchased the current residence about 10-14 years ago. A new roof was needed and as part of the deal, the seller paid for the project.
To reduce roof clutter a ridge vent was installed. During the roofing project, I took a look at how they were installed, to my dismay, the vents are blocked the entire length of the roof ridge.
So basically I paid extra for ridge vents that were improperly installed. As a possible result of the improper attic vent installation, I'm finding the plywood is delaminating and roof trusses are failing.

Does anyone think I should see if the company is still in business and file a civil suit in court to cover the costs and fix /replace the damage?

An awful lot depends on your states laws on small claims court use. If the company still is in business and has a point of contact (registered address at which to receive legal papers) which is within your state, you may do best in small claims court. Your recovery will be limited to the small claims court maximum, but your expenses will be small too. If you win, you still have to figure out how to collect, which could be hard if the company has no assets in your state.

Going for a full civil court suit would be economically riskier and would cost a bunch win or lose. And would definitely require the services of a lawyer.

Since the seller contracted for the repair but you are the one who was damaged, it could be difficult even in small claims court. Your only legal recourse might be against the seller, who would then have to sue the roofer to make good his losses.

[russ]

Actually 10 to 14 years late is 10 to 14 years too late

[Naptown]

Too put an interesting spin on this project,I need a bit of everyone's legal opinion on the following:

I purchased the current residence about 10-14 years ago. A new roof was needed and as part of the deal, the seller paid for the project.
To reduce roof clutter a ridge vent was installed. During the roofing project, I took a look at how they were installed, to my dismay, the vents are blocked the entire length of the roof ridge.
So basically I paid extra for ridge vents that were improperly installed. As a possible result of the improper attic vent installation, I'm finding the plywood is delaminating and roof trusses are failing.

Does anyone think I should see if the company is still in business and file a civil suit in court to cover the costs and fix /replace the damage?

A claim has probably gone past the statute of limitations.
Now the roof trusses failing has me a bit concerned with mounting the collectors to them.
sounds like you need to remove the plywood and at a minimum sister rafters to the sides of the top chord of the trusses. This will need to be sized so the rafter will be adequate to carry the loads without the added benefit of the truss.
Needless to say you will need to properly vent the attic this time around.