Mobile Home Roof Over Manual
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Many mobile homeowners attach porches and additions onto their mobile homes incorrectly. It’s not usually a detrimental issue, thankfully, but an incorrectly installed mobile home addition can pose problems. In this article, we are going to cover mobile home additions as thoroughly as possible. We’ll cover the advantages and disadvantages of adding to your mobile home and all the basics of building an addition or porch onto your mobile home, plus a few more important things you should know.
There are a few basics you should know before you decide to build an addition onto your mobile home.
The top priority for any homeowner considering an extension to a mobile home is to understand that the extension must not be connected to the existing structure. This implies that the extension should be constructed independently with its own footers. This ensures that the load of the new construction is evenly distributed into the ground rather than onto the original home.
A mobile home addition must move freely from the home itself. Porches, decks, and additions must have their own foundation or footers so the structure can shift independently of the home. The addition is simply ‘butted up’ and attached to the mobile home, and ‘sealed’ so nothing impedes the separate movement.
In other words, an addition should have at least 4 footers, one at every corner to transfer its weight to the ground. If you only see two footers at the ‘end’ of the addition (the side opposite the home), then it’s probably wrong and should be checked by a licensed profesional.
To put it simply, you aren’t attaching the addition to the home at all, you are building extremely close to the home and then sealing the crack between the home and the addition to prevent air and moisture leaks.
An addition needs a completely separate foundation from the home. And, like any structure, the footers must be placed below the frost line to keep them from shifting when the moisture around the cracks in the ground freeze causing the footers to heave and bow.
There are poured footers, cinder blocks, slabs, and piles. Footings for a mobile home addition should be determined by the depth of the frost line of your area, even if your home does not have the frost line footers so that shifting is minimal.
Here’s a map showing the frost line depths for the US:
Footers are installed below the frost line so that the addition doesn’t sink or shift.
Additions to manufactured homes are not often seen as an ‘improvement’ – meaning it probably won’t increase the value of the home in most cases. It won’t change the classification of a manufactured home from personal property to real estate unless the home is permanently installed.
A big disadvantage of building an addition on your mobile or manufactured home involves financing and insurance. It may be harder to obtain both if your home has been modified in any way. If you didn’t get the proper inspections and permits you may run into serious issues if you try to sell the home later down the road.
Some state mandates override local and county regulations when it comes to manufactured homes. Research properly for your location before you begin planning a mobile home addition. With some locations, you could run into so much red tape that the project ends before it even begins.
With all that said, mobile home additions are perfect projects for families that need a larger home but you must get permits and inspections done before, during, and after the construction process. Read about one manufactured homeowner’s experience while building an addition onto his single wide. He failed to get permits and inspections done and paid a price when he sold the home.
Sarah and Justin Wartick built an addition onto their 1985 Liberty single wide. You can see how they created the footers right up against the home and then framed the floor of it out (they were test framing the top in the first image). The second image shows the walls and roof have been framed and the floor joists being laid.
These next two images are the interior of the addition. The image on the right showing the door with the two steps is where the mobile home and the addition are attached. Technically, this is the only place the two structures meet other than where the roof and the siding are ‘sealed’ together.
There are some great online resources about mobile home foundations. This guide about manufactured home foundations and supports is invaluable.
For information about general construction footers, Front Porch Ideas and More has some nice illustrations that show the poured concrete and pier footings.
There are new products hitting the market to aid in DIY footings such as these square foot concrete forms.
You want the mobile home addition to having framing that is equal to or better than the framing that your home has. Of course, you’ll need to follow your local code.
Below shows a mobile home addition being framed out by SM Construction.
A great blog called Dovetail Blog shares its mobile home addition process in detail. It’s a small addition but the end results are beautiful:
As you can see, they used poured concrete footings and extended the roofline down to the addition, keeping the pitch. The addition looks to be used as an entryway that houses the stove and is a few inches lower than the home, except for a platform that the stove sits on.
Here’s the interior of the home:
You’ll have to determine the size of your opening from the home to the addition. Doorways are easier to close up should the home ever need to be moved or the addition removed.
If you do opt for a wider opening between the home and the addition you will need to consider support issues for the opening. Wider openings, where studs would need to be removed, will likely require support beams. That’s not the smartest move for mobile home perimeter walls because those are your load-bearing walls. In other words, keep the opening small so that it’s easier to seal around the home and to keep from needing to support the perimeter wall with a beam.
As stated previously, basic mobile home additions are not completely attached to the home. They are simply butted up to the home and then sealed all around to prevent leaks.
There are a variety of ways to seal the connection between the home and the addition. To seal the gaps between the home and the addition you can use weatherstripping, flashing, backer rod, caulking, and lumber. A backer rod is just a fancy name for round foaming that can be used as a membrane between the 2 structures.
There is a popular way to attach the siding of the home to the addition. Attach a 1×6 board to the home vertically so the addition will butt up against the middle of that board. You’ll attach another board with a lip to the side of the addition. Then, add weatherstripping and screw the lip of the addition to the board on the house – this brings the addition toward the home and helps seal it without overly damaging the home.
These questions were asked in the comment section of our very informative article about building mobile home additions found here.
Flashing and vinyl siding will cover it all up.
To connect the addition to the mobile home if the addition is lower than the roof on your home, you will need to use flashing to seal the gap between the home and the addition’s meeting points.
For a metal roof, you would tuck a single length of 18″ flashing, that has been bent to the needed angle, place the flashing under the homes roof edge and over the addition roof.
Attach to both with screws. Using 2″ neoprene flashing tape is always a good idea, and always seal the screws with weatherproof caulking (neoprene based).
One note about the flashing, you want as long a piece as possible, but you don’t want it too long. If the flashing is too long, it can cause cracks.
If the addition’s roof is higher than the roof on your home, you add the flashing under the lip of the roof of the addition and over the roof of the home (the opposite of above). This creates what roofing professionals call valleys and are problematic areas on any home. Special care should be made to keep water from sitting in the valley that is created.
The graphic below is based on a graphic found on Mobile Home Repair that shows a concept for sealing a mobile home addition. The top drawing shows a cap built on the home (labeled Alum Cap) and a piece of wide weatherstripping folded over to make a bulb shape and screwed into a board on the top edge of the addition.
The bottom drawing in the image above is showing the home and addition from the top, looking down. A flexible vinyl with fiberglass insulation is used to seal the sides of the addition to the home. It allows the needed movement required if your home is not set on a permanent foundation that is set below the frost line – the best method to prevent shifting of a manufactured home.
If the 2 roofs are at the same height, you just use flashing. Screw and seal.
When planning structural modifications or additions to a mobile home, especially those involving metal frames or support structures, understanding welding techniques becomes crucial. Mastering welding positions—such as flat, horizontal, vertical, and overhead—ensures that welds are strong, secure, and compliant with building codes. Whether you’re installing a steel foundation, reinforcing skirting, or crafting custom frames for extensions, proper welding enhances the durability and safety of your addition. A complete guide to welding positions empowers DIYers and professionals alike to work more efficiently and confidently on mobile home projects.
Below you can see a mobile home addition that passed inspection and can be found on The Inspector Blues blog.
It is independently supported, has wired smoke detectors, an exit, sits on an 18″ grade, and is built with pressure-treated wood. It may not be great looking but it had what it needed to pass its inspections and current codes are not lax at all.
Here’s a park model manufactured home getting an addition built onto it. Notice how they’ve done the roof:
Another park model manufactured home addition and carport built by HorseFly Construction:
The next photo shows a huge addition built onto a double wide manufactured home by Addon Rooms:
We’ve featured a few mobile and manufactured homes with additions:
The Directory of Mobile Home Manuals may help you find more information about your specific builder’s suggestions about mobile home additions here.
Here is a great resource from HUD about manufactured home foundations that explains everything.
The basic concept of mobile home additions is to keep the addition separate from the home, while still allowing a connection that is weatherproof and leak proof.
Inspectors and building consultants are available at your local and state agencies, use them to your advantage. You want a safe, long-lasting addition that will make your homework better for you and your family.
If you have any questions, please comment below and I’ll try my best to find you an answer. As always, thank you for reading Mobile Home Living!
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Hi Crystal,
We added on to our mobile home several years ago and the addition must have settled down because the mobile home is higher than the addition......the floor is slanted....I know i probably make no sense because I don't understand it myself but do you think we could maybe lower the mobile home to even it out? What kind of company would I call to fix something like this? I sure do love my home and have hope of fixing it. I hope you can help me.
Hi Samantha!
You make perfect sense! It does sound like the addition has settled or the home has become unlevel in some way or another.
I'm pretty sure it will be easier to raise the addition rather than to lower the home (but I'm no expert and an inspection would be needed). If the footers didn't go below the frost line the ground heave can make a structure uneven so this is kind of a common issue in the northern states (especially the old coal camp house where I'm from in WV because they were built so cheaply).
In the most simple cases, you'd just use hydraulic jacks and cement blocks to give the addition the proper height. I don't think it would be that expensive if it's just a basic sinking issue. Of course, there are always two ways of doing things when it comes to stuff like this: the right way and a way that gets it done good enough. The pro would probably tell you that the footers need to be redone completely and that would be expensive. You may be able to get buy with just jacking it up and adding new pier material to raise the structure. While I think anyone with basic construction experience could do this job you may want to try a manufactured home installer first since they are so experienced (and they deal with additions a lot).
Best of luck! Let me know how it goes.
I have a question about the opposite. I have a trailer with two additions. One on each side. I am in the process of purchasing a new modular that will go in the same place. I want to offer up the trailer for sale (cheap) and have it removed. I can't seem to find any information on the possibility of doing this without demo to the additions. Those will be a take em or leave em situation for the buyer. Would it be possible to move the additions too?
Hi Julie,
You can move additions. If you could contact a local transport company (house mover) and get an estimate of how much it will cost to move the additions that will help you sell the home. There are a lot of variables to the transporting of additions - build quality, footer, attachment to the home, etc. They should offer a free estimate but def make them come out and inspect them in person so they can see how the footers are done.
Good luck!
Hello,
Hope you can help me. We are in the process of having an addition built on. The existing home is on a concrete slab. Because of this the contractor said we do not need to raise it off the ground. Is this correct? All pictures I see show them elevated in some way so they aren’t sitting directly on the ground or concrete. We will probably have 4 steps that we will need to step down into it. Permits are also becoming quite confusing and the temptation to do it without is there I must confess. My question there is what issues will we run into with insurance? If something happened to the home would we be covered? What about if we went to sell the home down the road? Would we be unable to do so? And I’m not sure the home will be considered free standing. What exactly does that mean? It would have to be connected at the ceiling/roof level and the walls right??? Sorry so many questions but this is a big investment for us. Thank you
Hi Heidi,
If I'm understanding this correctly, you have a manufactured home and are building an addition on a slab foundation? With slabs, the concrete is the floor (or subfloor). They do this because it's a lot cheaper. Since the addition is being built onto a manufactured home it will be completely separate and have its own footers (nothing will be attached to the manufactured home structurally, though it looks like it is).
Before you do all this though I would recommend you have your manufactured home permanently installed to your state's guidelines and go through the hassle of having the home classified as real property. Your taxes will go up but so will the value of the home, especially once the addition is done (legally and with permits).
Doing any kind of modifications to a home without proper permits is a nightmare now. Years ago, it wasn't a big deal but now in order to do anything you need permits. The insurance company would absolutely have a reason to deny any claims and even if your manufactured home was permanently installed and classified as real property, any addition to it without permits would likely negate that classification (meaning you could only sell the home as manufactured and not real property which makes it lose a ton of value).
Hope that helps. Best of luck!
We had a "contractor" do our addition, we have a 16 x 76 home and added 16 x 32. After reading these comments I am a bit nervous. I watched them build most of the addition and I would like a little bit of clarification please. When you say free standing addition what exactly do you mean? When ours was built they attached the outside floor joist to the mobile home. It doesn't hold any weight from the addition, it is supported underneath by pillars and we framed out all of the walls in the addition, but it is definitely attached to the mobile home. The addition and mobile home could only be separated if we cut off the roof and unscrewed the conjoining floor board (32 ft long) that was screwed into the outside of the mobile home. I hope this makes sense.
What do we do now if this was not done correctly? The people who built our addition will definitely not fix it so it will be up to us.
Hi Cindy!
This sounds right. The addition will be connected or attached to the home (at the floor, walls, and roof) but it will have its own support or foundation. The pillars your contractor poured (assuming there are 4 or more), will be holding that weight, not the home. All sounds well!
How can you say all sounds well? You stress not to attach additions to a mobile but he is saying it was attached.
Hi Chris,
I understood her comment as saying the addition had its own footers and there is no weight on the home? Ledger boards and other materials will still be "attached" to the home but the addition will move independently from the home and all weight will be transferred to the footers. I may have understood her wrong?
Don't know where to start.
We own a Modular in Peyton Colorado - almost 1800 Sq ft. Want to look into a remodel/addon. Would like the add-on to have separate entrance with possibly a kitchenette with bathroom. Should we just do a whole separate structure or should it be an add-on?
Hi Jennie,
Technically, a modular is a site-built home so an addition would be attached to the home and considered as added equity. It's completely different from a manufactured home addition which is not attached to the home.
In this situation, I would look at the effect on the home's equity and taxes. Would it increase the home's value more as a separate building or as added square footage? Are the taxes going to raise more as added square footage or as a separate unit?
Best of luck!
Hi Crystal, question for you; if you build a Separate structure above a double wide mobile home with footings and possibly a center beam in the center of the manufactured space could that be a way to put a second floor without compromising the original mobile home structure? Any thoughts?p
Hi Pam,
Hmmm...good question! I've seen decks added over single wides in FL and SC (near beaches mostly) that had that kind of framed structure and they all apparently passed code. Something like that would definitely need to have its own support structure but as long as it spanned over and around the manufactured home, I don't see why it couldn't be done. It would probably be really expensive, though. I've seen manufactured homes jacked up so high it acted as the second story so if that's possible I'm sure the other way is as well.
If you do it PLEASE take lots of photos and notes cause I'd love to feature it!
The people who built my house built a block wall all the way around it now the motorhome sits flush with its pop wall but there's a gap between the top of the block and the mobile I know this can't be right Critters and all sorts of stuff can get down there I have pictures I don't know how to upload them I will try Monroe what you recommend to seal the house to that stem wall I know I shouldn't feel it completely cuz the underneath has to breathe any help and guidance it would be very thankful
Hi Christopher,
You will want to seal that up with something. I would probably just use some a wide rubber seal (if it's just a couple inches or so). If it's more than 5" you can cut down tin or sheet metal and frame it out somehow.
The formula for skirting ventilation is 1 square foot of vent to 150 square foot of floor space. Sealing this gap should help reduce your heating and cooling costs a little, at least.
Best of luck!
I live in a manufactured home on private property outside the city limits of Lancaster, California. I would like to expand my bedroom. It has a large window on the west side where I would like to place an addition with a large entrance into the expanded area. If I just take the window out and make a large doorway there, do you think there would be a problem? I'd also like to know whether manufatured expansion modules are available and who mkes them? My house sits on a foundation and I would extend my foundation out to accommodate the new addition, but it is my understanding that I should not attach my room addition directly to my manufactured home?
Hi Charlien!
You are correct, you will not attach the addition to your home. It will simply be butted up against the home and then the siding and roofing will be connected in a way to make it appear to be a single unit. You should be just fine - the easiest way to create an opening for an addition is to use a window because the framing that requires support is easier to work with. I've seen screened room kits but I'm not aware of any true addition kits though I'm sure a contractor in your area will offer a package deal on a per square foot basis.
Best of luck!
Crystal, love the post but I have a question on an addition I have been wanting to do for a while now, so I live in a mobile home park in san Bernardino county area, and the mobile home I happen to live in already has an addition with what used to be the porch so that is a toy room now so over the years it appears to be to small, and I want to extend it the room for it to be wider, the room right now is roughly 7ft wide and 16ft long and I wanted to extend all the way up to the end of my property line which is an extra 6ft more which would be amazing to have.But before any construction I wanted to know if any of that was possible or if I had to go to maybe the city hall I dont know any of that paper work stuff but I want to get your opinion on it and see if that was possible, thank you please get back to me as soon as possible i will greatly appreciate it.
Hi Alex,
You'll most likely need a permit for that, especially if that addition has wiring in it. Your home could very well have a retired title (with additions it's common) which treats it as a regular home (or real property). Call or Google your county's building permit department and give them a call.
Best of luck!
One thing I can not seem to find a definitive answer to is this: Can I cut thru my EXTERIOR wall... to create a larger opening that goes into my new addition, or to add a door/window where there was none?? I have not come across the full, complete explanation of this yet except; "Too hard" or, "I wouldn't do it" or, "Call a MH contractor"... Not helpful to those of us who need to be DIYers... so let's brainstorm this!
We have a SINGLE WIDE, 34 foot long by 12 foot wide. We are adding on another room, off the living room slider door area, to expand said living room. Am I stuck with just that 6' slider door hole being the only opening? Or can I cut the exterior wall back a few more feet on either side of the opening to make it all 1 smooth walled room? The front corner of the mobile home will stay as is- no changes. As I understand the corners of the exterior walls are integral to the load bearing job. But I'd like to get a few more feet of openess on either side of that 6 foot slider door hole. Usually, in a stick built house, I would add a header beam and support posts at the correct size per span foot, etc. Not sure how to do that in a mobile home where the main structural load integrity is at the exterior walls built on a chassis.
AND: Can I cut a new doorway into an exterior wall? I'd like to cut a whole new door into the rear master bedroom where there is none. The whole wall is solid from the back corner all the way until the kitchen window; a good 20 feet. It used to be the closet. I removed that and built a laundry room right on the other side that I want to convert to a bathroom. But I need access! I need that door. Can I just frame it out like a regular house with proper header and supports?
NEXT is this brain teaser: The previous owner had a contractor build on a bedroom off the dining room area. The access door way is the old rear exit at the back of the hallway. All done very well, EXCEPT...they LEFT the bump out dining room wall there; they just removed the windows and dry-walled around the pillars/frames of the bump out windows! It looks ridiculous! While sitting in the dining room, you'd be able to watch the poor guests in the bedroom! Not very practical. So I'd like to just open the 2 windows on the left (from ceiling down to floor- they will be opening up into the new living room we're adding...see above) and wall up the one on the right. I don't think bump outs (or Expandos/Tip Outs/Whatever you call em), are load bearing or supportive as far as walls go. Will I have structural problems removing those 2 old bump out window frames and pony wall under them??
So really, not only will I be opening up the 6 foot slider door hole, but removing the whole exterior wall next to it that runs to that bump out. Hmmm. That would probably be removing about 1/3rd of the exterior wall of the entire trailer (about 10 feet of a 34' mobile home). If I can't do that, I'm left with an awkward L shaped space instead of 1 square great room.
SO... long story short. CAN I CUT INTO AN EXTERIOR WALL? If so, how much? If it's larger, how do I rework load bearing capabilities? Can we start a whole forum for this?? Thanks!
In 1977 my dad put two older single wide mobile homes together and connected them with an eight foot framed out opening in the wall.
Hi Hunter!
I would love to see pictures! I've had a vision in my head about bringing in another single wide and attaching it to ours. I'm always curious to see how others have done it.
Thanks for reading and commenting!
Hi!
I'm not a professional but with every addition I've seen first hand an opening is cut and trimmed out like you would with a door or window. You don't want the opening to be too wide so and I'm gonna have to say that opening up 1/3 of the home's length will create some serious structural integrity issues on the home. There will need to be a lot of math done so that you know where to put the new posts and beams to support the weight and hold the integrity of the perimeter. Professionals really need to be involved in every step.
I hope more knowledgeable readers can add their thoughts to this comment. I don't know how to create a forum so we're stuck with the comment threads. Best of luck!
Best of luck!