Basement insulation is two jobs under one name. The first is the rim joist, the band of framing that sits on the foundation and caps every floor joist, and it is the cheapest air sealing in the house. The second is the foundation wall, worth doing when the space is heated, finished, or holds the furnace. Heat loss through uninsulated foundation walls has been measured at up to a third of the heat loss from an average house, and a Burlington basement is rarely empty.
The housing decides which version you need. 64.4% of the county’s units are detached and 14.5% are townhouses and duplex halves, with 31.2% of everything built in the 1960s and 70s and another 13.9% in the 1940s and 50s. Those are the decades of the poured or block cellar under a ranch, split or tract colonial. Electricity heats 19.1% of occupied homes countywide, 23.7% in Delran and 21.5% in Burlington Township, where a cold basement runs up a bill fast.
Where basement insulation pays in Burlington County houses
The split-level band joist. A split has a band joist at every change of level, not just one around the perimeter, and each one is a strip of bare wood with house air on the inside and winter on the outside. The 1960s and 70s account for 43.5% of Cinnaminson, 46.3% of Delran and 61.4% of Willingboro. In those houses the rim is usually bare or stuffed with a batt that lets indoor air reach the cold wood behind it, which is how you get a cold floor over a warm basement.
Old cellars in the river towns. The county’s pre-1940 share is 10.7%; in Moorestown it reaches 23.8%, with 16.1% more from the 1940s and 50s, and Burlington Township runs 7.7% and 15.4%. Stone and rubble cellars do not take a flat board: the hollows behind it fill with house air that finds the cold wall. Those walls take sprayed foam in full contact instead, and the sill above them is usually the leakiest line in the building.
Finished basements in the newer townships. The 1980s and 90s account for 54.4% of Mount Laurel and 48.9% of Evesham. Plenty of those basements were finished by an owner or a handyman with studs against the concrete, fiberglass between them and a sheet of plastic over the lot. That wall is the one the Department of Energy tells homeowners to refuse: the concrete is damp or drying, indoor air slips behind the batts and condenses, the fiberglass holds the water and the plastic stops it drying out.
The half-basement, half-crawl house. Splits and rear additions across Medford, 35.9% of it built in the 1960s and 70s, and Pemberton Township at 47.6%, sit on a foundation that changes halfway. Insulating the basement walls and leaving the crawl space open to the outdoors leaves the same floor half inside and half outside, so the two get quoted together or the cold spot simply moves.
Basements that hold the mechanical system. With 70.0% of occupied homes on utility gas, most of these houses keep the boiler, the water heater and the duct trunk downstairs, which makes the basement part of the heated house whether anyone meant it to be or not.
How we do basement insulation in Burlington County
Water is settled first, every time, because insulation added to a damp basement makes the dampness worse. We look for cracks that weep, standing water, damp patches, white chalky efflorescence on block, condensation on pipes and the smell that goes with all of it. Gutters and grading belong to a gutter installer or a landscaper; interior drains, sump pumps and exterior work are a waterproofing contractor’s trade, not ours. If the source of the water cannot be removed, the wall does not get insulated. Radon is tested before air sealing, since tightening a house can concentrate it, and mold on the framing goes to a remediation company first.
The rim joist comes next, and often first in the budget. Closed cell foam sprayed into each joist bay joins the foundation, the sill, the rim board and the subfloor into one air barrier and keeps indoor air off cold wood. The code lets rim foam stay uncovered within its published thickness, density and flame-spread limits, and the quote names the limit the product works inside. Where foam is not the right call, board is cut to each bay and sealed on all four edges, or batts go in after the rim has been air sealed separately.
On the walls the rule is that only moisture-tolerant material touches concrete. Closed cell foam at R-6.9 to R-7.1 per inch is sprayed straight onto poured, block or stone, filling every irregularity and acting as a vapor retarder at the same time; just over 2 inches reaches R-15. Rigid board is the cheaper route on a flat poured wall, glued in full contact with every seam sealed so no air gets behind it, and kept to the thickness that still lets the wall dry inward. A stud wall in front carries the drywall, bottom plate on a sill gasket, board held off the slab, and latex paint rather than vinyl wallpaper on the room side. No polyethylene goes into a basement wall here.
Insulation runs from the top of the wall to the floor, or to 10 feet below grade if that comes first, and where only part can be done the top of the wall matters most. Old wet or rodent-fouled material comes out under containment, and the white vinyl-faced fiberglass blankets hanging in many unfinished Burlington basements come down rather than get covered, since they hold fiberglass against concrete behind a vapor retarder. Foam on a basement wall needs a thermal barrier over it, ordinarily half-inch gypsum board hung by the finishing trade, and foam plastic needs a permit in New Jersey, which we pull with the job. The ceiling is the right plane only in a dry, unheated basement with no ducts, equipment or exposed pipes, and there it buys quiet more than energy.
What basement insulation costs in Burlington County
Most of our projects run between $3,500 and $12,500. A rim joist package in one ranch is the small end of that range; a full perimeter of foamed wall under a Mount Laurel colonial, with a finished ceiling and bulkhead to work around, is the top. The number follows linear feet of rim, square feet of wall, how many bays are blocked by ducts, pipes and a panel, whether the wall is flat enough for board or rough enough to need spray, how much old blanket insulation is coming out, and whether the same visit covers a crawl space under the addition. Drainage, crack repair and drywall are priced by the trades that own them. Our insulation cost guide sets out the parts.
Rebates for basement insulation in Burlington County
The utility that runs your project is the one whose name is on the bill. PSE&G supplies gas and electricity to Burlington Township, Cinnaminson, Delran, Moorestown, Mount Laurel and Willingboro. Pemberton Township buys electricity from JCP&L, with PSE&G gas reaching only a corner of it. Evesham and Medford split both meters, electricity between PSE&G and Atlantic City Electric and gas between South Jersey Gas and PSE&G. Where the two bills carry different names, either program can take the job; begin with the company that bills the fuel doing the heating, because the gas programs require gas heat.
Whole Home Energy Solutions pays on a project that includes air sealing and the insulation the assessment calls for, which is how a basement scope is built in any case: seal the rim, then insulate the rim and the walls. PSE&G pays up to $7,500 and adds 0% on-bill repayment of up to $25,000, beginning with an assessment by a BPI-certified contractor participating in its program, who sets the fee. JCP&L and South Jersey Gas publish their arithmetic: $2,000 for a modeled 5% energy saving plus $200 per point above it, capped at $7,500 and at half the project cost, each with 0% financing of $2,500 to $25,000. Atlantic City Electric pays up to $7,500 on single-family residences and finances through the program’s lender. Whether any installer, this one included, participates in the program you choose is a question worth asking before you sign.
Income-qualified households can have the work done at no cost through PSE&G Home Weatherization or the $14,000 weatherization programs at JCP&L, South Jersey Gas and Atlantic City Electric. New Jersey Comfort Partners covers households at or below 250% of the federal poverty guidelines, $82,500 for a family of four in 2026, and sends oil, propane and kerosene homes to the state’s weatherization office. New Jersey’s IRA Home Energy Rebates have not launched and the state still calls them in development. The federal 25C tax credit ended for anything placed in service after 31 December 2025. See our New Jersey rebate guide for the detail.
Code and climate in Burlington County
Burlington County is climate zone 4A. Under the 2024 IECC, adopted in New Jersey on 17 August 2026, a basement wall in the zone 4 counties takes R-10 continuous or R-13 cavity, which is about 2 inches of extruded polystyrene or a little over 1 1/2 inches of closed cell foam. The zone 5 counties in the north of the state need half again as much, so a specification copied from a Bergen or Morris job overbuilds a Burlington wall. In the energy code a basement wall is one that is at least half below grade and encloses conditioned space, continuous insulation is the unbroken layer, and cavity insulation is what fills a stud wall inside it.
Two more rules shape the work. The residential code exempts basement walls from its vapor retarder requirement, so no kraft facing and no polyethylene belongs in that assembly, and the 2024 edition bars a Class I vapor retarder from acting as the air barrier below grade. Foam plastic, sprayed or board, sits behind a thermal barrier unless it meets one of the code’s exceptions, the rim joist being the common one. Existing houses fall under New Jersey’s Rehabilitation Subcode, so insulating a basement does not drag the rest of the house up to current code.
Towns we serve in Burlington County
Basement and rim joist work goes on in all 40 of the county’s municipalities. These nine have their own pages.
Common questions about basement insulation in Burlington County
Should I insulate the basement walls or the cellar ceiling?
Walls, in most Burlington County houses. The walls are the answer when the basement is finished or will be, when it holds the furnace, water heater or ducts, or when it has ever been damp, because insulating them brings the space inside the heated house. The ceiling suits a dry basement that will stay unheated with no equipment and no exposed pipes, and what it mainly buys is quiet between floors. Doing both rarely pays once the walls are insulated.
How much does rim joist and basement insulation cost in Burlington County?
Most of our projects run between $3,500 and $12,500. Sealing and foaming the rim joists of a single Cinnaminson ranch is a small job near the bottom of that range. A full perimeter of insulated wall costs more, and it moves with the square footage, the roughness of the foundation, the number of bays blocked by pipes, ducts and the electrical panel, how much old blanket insulation has to come out, and whether a thermal barrier and drywall follow behind us.
Does a Burlington County basement wall need a vapor barrier?
Not a plastic one. The residential code exempts basement walls from the vapor retarder requirement, and polyethylene over studs and fiberglass is the detail that traps water against concrete and grows mold. What the wall needs is an airtight, moisture-tolerant layer in full contact with the concrete: closed cell foam, which is its own vapor retarder at a couple of inches, or sealed rigid board. Keep the room side able to dry, so latex paint rather than vinyl wallpaper or an oil finish.
Can you waterproof a basement in Burlington County?
No, and we will say so at the estimate. Interior drains, sump pumps, crack injection and exterior excavation are a waterproofing contractor’s trade, and prices for that work come from them, not from us. What we do is the part that follows: air sealing, rim joists, foundation walls and the crawl space next door, once the water has been dealt with. Insulating over an active leak wastes the money twice, so the order of the trades is written into our scope.
Free energy audit in Burlington County
Downstairs we work around the perimeter with a flashlight: the sill and rim at every bay, including the bays buried behind ducts and pipes, the foundation wall top to bottom, the slab and its joint with the wall, the bulkhead or hatch, the windows, and the equipment that sits down there. We note the moisture evidence, what insulation is already up and what condition it is in, and whether the basement is heated in fact if not on purpose.
You get a written scope and a price for our part, free and with nothing owed. Call 914-554-2289, 8am–8pm, seven days. The Home Insulators has been family-owned since 2015, works out of New Rochelle, NY, and sends its own 100-plus-person in-house crew; we never subcontract.
Get my free estimateor call 914-554-2289, 8am–8pm every day