NR Building Solutions

Exterior & envelope

Belly wrap and underfloor insulation on manufactured homes

Close the underside of the home before anything is installed on top of it — this is the sequencing error that costs the most money in this category.

Request a bid(713) 923-0835
How it is priced
Per home for full replacement, per repair location for patching
Timeline
Set in your written estimate, after the walk-through
Who performs it
NRBS crews, self-performed

What the belly is, and what it does

The belly wrap is the sealed membrane running across the underside of a manufactured home, below the floor joists. Some people call it the bottom board or the belly board. It holds the underfloor insulation in place and it separates the inside of the floor system from the ground.

It is doing two jobs. It keeps the insulation dry and in position, so the floor performs thermally. And it keeps ground moisture, animals and debris out of the floor cavity.

On most homes in most communities built before about 2000, it is torn somewhere. Usually in several places.

The sequencing rule, and why it is the expensive one

The belly gets closed before anything is installed above it. Every time.

This is the single most costly sequencing error we see on manufactured housing renovation programmes, and it is common because the belly is invisible. Nobody walks a unit and notices the belly. They notice the soft floor.

Here is the mechanism. A torn belly lets ground moisture into the insulation. Saturated insulation holds that moisture directly against the underside of the deck, continuously, in every season. The deck softens. Someone replaces the deck, lays new flooring over it, and closes the job.

The new deck is now in exactly the environment that destroyed the old one. It fails on roughly the same timeline. The second repair costs more than the first, because this time the finish flooring is scrap as well.

Patch or full replacement

When it is right

Patch
Few tears, localised, insulation around them dry
Full replacement
Tears in several bays, insulation wet or displaced across the home

Insulation

Patch
Replaced only at the repair locations
Full replacement
Removed and replaced throughout

Time

Patch
Shorter: a localised repair
Full replacement
Longer: the whole underside. Set in your written estimate

Do it anyway when

Patch
—
Full replacement
The home is getting a full remodel, and the underside is open while everything else is.

What a proper repair looks like

A belly repair is patched with the same polyethylene material and sealed — not stapled fabric, not tape over a hole, not a piece of house wrap. A repair that is not sealed is an entry point again within a season, and rodents find it faster than anyone expects, because the insulation on the other side is nesting material.

Where insulation is wet, it comes out. Wet insulation does not dry in place under a sealed belly; it stays wet and it keeps working on the deck above.

Doing it at community scale

Belly work across a group of homes runs on one mobilization: access, staging and material are set up once for the group rather than once per home. If you are planning subfloor or flooring work across a community, price the belly across the same set of homes rather than home by home: request a park-wide quote.

Also in exterior & envelope

What the price covers

In the scope

  • Belly material: Polyethylene bottom board, seamed and sealed to the frame
  • Insulation: Batt or blown, replaced wherever it is wet or compressed
  • Repair standard: Patched with the same material and taped — not stapled fabric
  • Sequence: Belly closed BEFORE subfloor, flooring or skirting

Not in the scope

  • Anything not written in the scope. Extra work found on site is raised as a written change order before it is done.

How the job runs

  1. Walk-through

    We walk the units or the roof, or work from the walk sheet you already have.

  2. Written scope

    A written scope and price before any work starts, priced as shown above.

  3. The work

    Our own crews do it, to the written scope. Anything extra is a written change order first.

  4. Final walk-through

    We walk it again with you and close out anything on the punch list.

Step one is your scope, as it already exists.

Request a bid

Pricing a whole community? Request a park-wide quote.

Common questions

It is the sealed membrane across the underside of a manufactured home, below the floor joists, holding the underfloor insulation in place and keeping ground moisture and animals out. It is sometimes called the bottom board or the belly board. On most older homes in a community it is torn somewhere.

Because everything above it lives in the environment it defines. Replace a subfloor and lay new flooring over an open belly and the new deck sits in exactly the conditions that destroyed the old one. The failure returns on roughly the same timeline, and the second repair costs more because the finish floor is now scrap too.

Animals, plumbing work done from underneath, road debris during transport, and age. Rodents are the most common — a small entry becomes a large tear because the insulation above it is nesting material.

Patch when the tears are few and localised and the insulation around them is dry. Replace when there are tears in several bays, when the insulation is wet or has been displaced across the home, or when the home is getting a full remodel anyway and the underside is already open.

W-9, written safety programme and certificates of insurance (GL and workers’ comp): being prepared. What is published so far is on vendor credentials.

Usually specified alongside

Where we perform belly wrap & insulation

Self-performed crews based in Houston. Each city page carries local housing context.

Houston-area city pages