Spray Foam for Michigan Cottages and UP Camps: Seasonal and Off-Grid Applications

## Spray Foam for Michigan Cottages and UP Camps: Seasonal and Off-Grid Applications

Every November, roughly the same scene plays out across Emmet County. A family from downstate locks up their Petoskey-area cottage, drains the pipes as best they can, and hopes for the best until April. Some make it. Some come back to burst pipes and wet insulation sagging in the crawl space — insulation that was never built for a home that goes dark for five months.

A seasonal home is a different problem than a primary residence. It needs a different answer.

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## Why vacation homes fail at winter insulation

Michigan has more vacation properties than any other state except Florida — around 1.4 million. A significant chunk cluster in the northwest Lower Peninsula and the Upper Peninsula: Leelanau County shoreline cabins, Charlevoix cottages, camps on Lake Superior’s south shore that Yoopers’ grandparents built in the 1950s.

Most of them were built with fiberglass batts. Fiberglass absorbs moisture. In a home with no HVAC running between October and May, that moisture has nowhere to go. Mold grows, R-values drop, and by the time you are heating the place each summer weekend your propane boiler is working 40% harder than it should — because the insulation in your walls is doing 40% less than it was when it was new.

Spray foam does not absorb moisture. That one fact changes the math on a seasonal camp.

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## The installation timing problem

Here is where people get into trouble: spray foam has temperature requirements. The substrate — your walls, rim joists, crawl space floor — needs to be above 40 degrees Fahrenheit for the material to cure correctly. In Leelanau County, that window closes in October and does not come back until late April.

If a contractor sprays foam into a 28-degree crawl space, you get poor adhesion, incomplete cure, and foam that shrinks away from the rim joist it was supposed to seal. You have paid for insulation that is not actually insulating.

### What good timing looks like for a UP camp

For a camp near Munising or the Keweenaw Peninsula, your realistic install window is mid-May through September. That is plenty of time. The problem is demand — every contractor in Marquette and Alger Counties is booked through July with new construction. If you want spray foam done before Labor Day weekend, you are calling in February.

Plan the installation the winter before you want it. That is not upselling — that is just how the northern Michigan contractor calendar works.

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## Off-grid applications: the propane math

A lot of UP camps run entirely on propane — no DTE line, no Consumers Energy meter, just a 500-gallon tank and a delivery truck. In that situation, insulation is not a comfort decision. It is a fuel cost decision.

A 900-square-foot camp with fiberglass batt walls and an uninsulated crawl might burn through 400 to 500 gallons of propane over a three-month winter stay. Spray foam on the rim joists, crawl space, and attic floor cuts that by 40 to 60 percent. At the propane prices Yoopers have paid lately — $2.80 to $3.50 per gallon depending on how far out you are — that is $450 to $875 back in your pocket every winter.

The installed cost of spray foam on a 900-square-foot camp, focused on the high-impact areas, typically runs $3,500 to $6,000. On the propane math alone, you are looking at a four to eight-year payback. For a family that plans to pass the camp down, it is not really a question.

### What if the camp sits empty all winter with no heat at all?

This is common in Alger County hunting camps — the propane gets shut off in November and nothing runs until April. Spray foam still makes sense here, maybe more so. Closed-cell foam on the rim joists and foundation walls keeps ground moisture from migrating into the structure and keeps the wall cavity temperatures above the dew point longer into the fall. You are not heating the camp. You are protecting the building from the winter it sits through without you.

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## Pipes and the insulation-made-it-worse problem

There is a mistake that shows up in cottages along the Traverse City corridor and up through the Old Mission Peninsula. Someone insulates the crawl space walls but leaves gaps in the rim joists. The pipes run under the floor. In a properly sealed crawl space, ground heat keeps pipes from freezing — but only if the space is actually sealed. A partial job changes the airflow without protecting the pipes. Cold air finds the gaps. The pipes end up in a colder microclimate than before the insulation went in.

This is why it matters who does the job, not just what material they use. Spray foam in the right places keeps pipes viable. Spray foam applied without understanding how your specific crawl space breathes can create the freeze risk it was supposed to prevent.

For seasonal homes in the Charlevoix area — especially those with plumbing along exterior walls — the safest starting point is closed-cell spray foam on every exterior rim joist, fully continuous. It air-seals and insulates in one pass. Nothing else does both at that thickness.

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## Ice fishing shanties: same principle, different structure

This is specific enough to northern Michigan that it is worth a quick mention.

A portable shanty does not need spray foam. But a permanent fish house — the kind dragged out onto Houghton Lake or Big Bay de Noc in January for a six-week stretch — can benefit from it. Closed-cell foam on the floor and lower walls adds structural stiffness, cuts drafts, and gives you some extra flotation margin if ice-out comes early. The application is thin: half an inch to an inch on the floor, an inch on the lower walls. On a standard 8×16 shanty it costs a few hundred dollars. The propane savings over a six-week season are real, and your feet stay warmer at the bench.

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## Frequently asked questions

**Can spray foam be installed in a Leelanau County cottage with no power running during the winter?**

Yes. The installation requires power for the spray rig, so the work happens during the active season. Once the foam cures, it needs nothing to keep performing. A cottage that goes dark from October through April is actually an ideal candidate — the foam protects the structure all winter whether or not anyone is there.

**I have a camp near Munising with a well and septic. Does spray foam affect either one?**

No. Foam applied to the crawl space and rim joists does not interact with your septic or well. The one thing to sort out is whether your pressure tank and exposed water lines fall inside the thermal boundary the foam creates. If they sit outside it, they are still freeze-exposed. Worth checking before the job is done.

**My Charlevoix cottage is from the 1960s with tongue-and-groove walls and no vapor barrier. What should I know?**

Older cottages in that era were built to breathe. Adding closed-cell foam to the exterior side of those walls changes the moisture dynamics in ways that are not always straightforward. The safer approach is usually to start with the rim joists and crawl space — the highest-impact areas — and assess from there rather than spraying full wall cavities without a moisture audit first. Make sure whoever you hire has experience with older northwest Michigan cottage construction, not just spray foam work in general.

**What does a full job cost on a UP hunting camp?**

For an 800 to 1,200-square-foot camp, focused work covering the crawl space, rim joists, and attic floor typically runs $4,000 to $8,000. That range moves based on access, current material costs, and drive time — Marquette County pricing is different from what you will see near Escanaba. Most camp owners start with the crawl space and rim joists, watch the propane numbers the following winter, and decide from there whether to expand.