Insulated Skirting Question


#1

Does anyone have experience with insulated skirting? Up here in the north, it gets us out of foundation issues regarding frost, plus it has other benefits for frozen pipe concerns. Does anyone know how much more expensive it is to get installed and also if it is easily removeable for access to the home.

Our foundations up here are about $2,000 each for frost depth requirements. If insulated skirting can get that down to $500, plus provide additional benefits, it seems like an easy decision assuming contractors can still get under the home after the skirting is installed.

Thanks everyone and good luck out there.


#2

This is a great question and a great money saver…if it’s legal to do something different w.r.t. lot prep because of it. If lot prep is identical then savings in heat loss is only benefit I see, which is great but the extra cost and hassle is a trade off at that point.


#3

JWR,
Can you elaborate when you state that insulated skirting allows you to get out of foundational frost issues? Is that confirmed by your state and HUD?
For example, we are licensed installers in WI. In our area the frost line is considered 48". As such for the installation of homes newer than 2007, we have several ‘approved’ foundational installation methods:

  1. Concrete slab
  2. Concrete piers (48" deep)
  3. Basewall/Frost Protected Shallow Foundation
  4. Helical Piles (drill down 7 ft)

For our new homes, we have installed regular and insulated skirting (Rapidwall). It costs us about $1400-1600 for the Rapidwall. And we can tell you average temps are about 7-10 degrees warmer with the Rapidwall.

However, the insulated skirting does not have get us out of the required foundation methods nor remove any frost requirements.

Of course this is for WI. Not sure how your state’s requirements are.


#4

What are helical piles? And what is the shallow foundation method?

What does lot prep run you, @howardhuang33 , and which method do you use?


#5

Brandon,
Costs vary greatly. Also, we are vertically structured so we can do almost all the install in-house and have the tools. So costs are not equivalent. For a new home we have initial lot prep which costs about $500-700 plus any electrical/gas work. Then the foundation and setup work comes.

  1. Here is a helical piles video: https://www.youtube.com/watch?reload=9&v=HJVzCpLsozw&feature=youtu.be
  2. Here is image of a frost protected shallow foundation for MH

Concrete piers are the most cost effective and we have cement poured for about $1100 for a 16x80. Remember that we drill all the holes and do the rest.
Basewall may cost us $3-4 and helical piles about $6-8k. Concrete slabs are the one type we do not do at our community (ie we do not do the work. Homeowners can pay for this at their cost).


#6

Michigan is a HUD state so we go with the HUD guidelines. Champion tells us they have approved alternate methods instead of drilling piers so I looked into them. The only cost effective method had to do with an existing slab. Assuming the slab is in good condition, and not too cracked up, Champion tells me I can pour a 4" cookie on top of the existing slab to give me an 8" total footing depth. This doesn’t help with frost but gets my footing strength to where it needs to be. The insulated skirting allows me to ignore frost completely according to their documents. So, I need my HUD 309 inspector to sign off on it and also the local building department (they inspect footing and life safety for parks). Even if my existing slab is not in good condition, I can sawcut the existing slab where my footings are located, dig out an extra 4" of dirt, and fill back to existing slab grade with concrete to provide my 8" footing. That is a lot less expensive that drilling the full 42" depth required where we are. Plus, I don’t need to worry about hitting water or utility lines which is always a concern. We have hit water and gas lines in the past and it is a real problem. I don’t mind drilling the piers but drilling below grade concerns me a lot especially when I have to go 42" deep.
Other manufacturers have offered going half the depth for footings (21" instead of 42" in MI) if we use insulated skirting. The cost for the skidsteer is pretty much the same so in that case I only save on the cost of concrete which is about $500. Not worth it.
FYI ask if your home manufacturer if they will provide stamped paperwork saying you don’t need any footing other than a 24" W cookie if you are in sand soil conditions. Our local building department allows us to go 24" depth for regular home footings with sand soil but HUD’s are supposedly getting away with a standard cookie.


#7

Howard, very helpful and informative posts…thank you!


#8

JWR,
Sounds like you have reviewed this in depth. Every state and manufacturer is different. So its best to go with what you have reviewed as best practice and approved!

I’m not knocking floating concrete slabs, as every method has its pros and cons. Slabs make setting and skirting much easier. But unless there is insulation under and around the slab and backfilled, the frost will take over a floating slab of 4-10" regardless in cold climates where the frost like 3ft+.

Last year, we had one brand new home with new slab and insulated skirting. It was the only home in the park that had the sewer line freeze. The outside ambient temperature was 8* and it was 10* under the home. Guess what, the slab was freezing cold. In fact, we had old homes on dirt and regular skirting which were above 32*.

FYI - One good experiment we have done is bought outdoor thermometers with remote readers. We place them under our new set homes to evaluate how well they insulate. We have 3-4 different foundation and skirting methods so this is a good experiment.


#9

Great stuff thanks Howard

Would you be willing to share a bit of background on how you built your own Installer crew? Did you take a skilled handyman you were working with an help him get licensed?

Over in Michigan the new HUD rules kicking in has created a significant shortage of installers. At this point it might be easier for me to just encourage and help one of my contractors to get licensed.


#10

Thanks Howard. Good tip on the temps for homes on slabs. I will take that into account. If you had to choose, would you demo the slab and truck in dirt to bring up the grade? Or would you use the existing slab to save money? Using the existing slab will probably cost about $2000 more per house. Maybe more depending on existing grades. Thanks for all the tips.


#11

Hi Noel
Fortunately for us, our facility manager has been with us for a while and already had 30+ years experience as a mover, setter, manager and do everything guy. But with that said I would say:

  1. I am actually the licensed installer (keeps everyone honest if the owner understands)
  2. We still sub-contract other installers due to bandwidth but we monitor and QC everything…AND we learn things from other installers all the time.
  3. Yes, get your people licensed as well - its truly not rocket science. Yes there are definite nuances that only an experienced installer will bring but its not that difficult after you do a few
  4. Whenever we are doing something new, we hire out initially & pay very fairly but are up front that we want our guys to learn with them.

Simple example…for installing helical piles (7 ft deep) we were very worried about utilities. We bought our own utility locating equipment but paid a professional to come teach our guys how to do it properly. Its really not that difficult.


#12

JWR,
First can you help me make sure I understand MI rules:

  1. If you removed the slab and backfilled dirt, what type of installation method are you allowed to use or would you use?
  2. What is the cost differential between the methods for you? I’m guessing you meant that using the existing slab will cost $2k LESS per lot?

For $2k I would use the existing slab. But I would buy on infrared thermometer and start measuring temps under different homes and on existing slabs in your park.

PS: Here is one big reason I don’t like slabs for my particular park…old galvanized pipes. They break…a lot! If a pipe breaks under a slab then we have no choice but to move a home, break the slab, just to fix a water line. Think about that.


#13

Howard,

There are two types of insulation that we use at our park in Montana. The temperature get -20F to -35F over the last month before any wind chill. Our practice is to heat tape and pipe wrap the water supply line and do nothing with the waste line. We had a few problem with unoccupied units during the recent cold snap to trailers that we recently brought into out park. Interestingly it was the waste lines that froze.

Moving water does not freeze so waste line are normal no a issue but with an unoccupied units and limited water flow ice started to build up and eventually froze the 3" main waste line both under the trailer and the 2’ section that not under the trailer. We used a diesel bullet heater under the unit for a few hours and got the pipe unfroze enough to allow water to flow and then ran hot water to clear the rest of the line. This all happened when the high temperatures were -15F

As for insulation we have nothing, spray foam or fiber glass bats on the skirting. Spray foam is a very good solution because it stops drafts that, in my opinion, are more important than the level of insulation. The reason I say that is I can heat up under any trailer with an 80,000 btu heater in the middle of winter as long as I don’t have the wind blowing all that heat away.

Now for cost. This is a business after all. Spray foam will run you $.75 - $1.50 per sqft one inch thick. The price will vary across the country and with the price of oil. Open cell foam is R3” and the low price. Closed foam is R6.5” and the high price. Either will work and 1" is sufficient.
Corbond is the brand I like the most. It is also the insulation I have had done in my houses over the years.

If you are looking for the most cost effective way to air seal the skirting buy a foam gun. It is much much better than the classic great stuff $3 can. It allows you to use as much or little as you need. See amazon link: https://www.amazon.com/GREAT-STUFF-PRO-Dispensing-Gun/dp/B0002YOMJE For less than $100 you can have your maintenance man craw under the trailer and seal any spot where light is coming in. This should air seal the skirting.

If you are looking for a better solution and are willing to spend ~$700 ish you can have your local spray foam insulation company spray inside under the trailer skirting. The nice part about this is it works in retrofit situations where you are having problems. You can also address any missing insulation under the trailer at the same time. This is most beneficial around where the main water line enters the trailer. The $700 was for a closed cell foam 14x64 trailer 30” off the ground. You should be able to do open cell foam for about half the price.

One last thought. If your slab that your trailer is sitting on is not insulated then the cold will just travel through the ground and under the skirting and the temperature under the trailer will still be close to the temperature of the outside.

So for me airsealing is by far the most important issue and insulation just makes unfreezing frozen pipe quicker and easier. Typically our tenant don’t have a 80,000btu heater and contact the on site manager to borrow ours. That being said frozen pipes are the exception and not the rule. Say 2-3% of our tenants per year.


#14

Regarding insulation…our manager at our community in Minnesota “commandeered” some 2" rigid foam scraps and positioned them behind the vinyl skirting, between the underside of the home and the ground all around the inside perimeter and then installed a radio frequency thermostat and monitored the temperature for one winter. The temperature never fell below freezing that winter with the insulation. Slowly, (and usually after a winter freeze-up) our other residents started copying what my manager did. This 2018-19 winter has been below zero for more days than I can count and (knock on wood) we have had no freeze-ups with the exception of a couple of residents not confirming the heat tape around the water meters was turned on. The material is very similar to this: https://www.homedepot.com/p/R-Tech-2-in-x-4-ft-x-8-ft-R-7-7-Rigid-Foam-Insulation-310891/202532856

Regarding the slabs: Over ten (10) year period, we now have almost all the homes on slabs. We increased the rent $100/month for homes on slabs and the break even is about 5-6 years. Minnesota is already highly regulated in manufactured housing and not long after we purchased the community, the laws in Minnesota became more strict regarding installs with newer homes and/or older homes moving around. What I did was read the installation requirements from as many manufacturers as I could find coupled with HUD install requirements and drew up my own slab that would (hopefully) meet or exceed any manufacturers specifications. It has extra rebar in it so the slabs can accommodate 14 or 16 foot wide homes.

Here is what I can tell you about slabs. They do float and move around, but the great thing about slabs is the whole house moves with the slab. If you use any other type of independent system, all the pieces move differently (independently) which tweaks the house around and requires re-adjusting windows and doors on a regular basis. Slabs are better insulated and they are (generally) not damp and eliminate a whole host of problems. Yes, they are expensive, but based on my experience in the northern climate where the frost depth is 4-6 feet, it has been very successful. I have attached the slab drawing that I personally made up and had approved by the local city engineer where our park is located. If anyone decides to reference this drawing , please consult your local inspector first OR the manufacturer with whom your homes are made. It would be nice if the industry as a whole would just adopt a standard foundation/installation for all manufactured homes.MH Slab.pdf (151.5 KB)