Why the site decides everything
A manufactured home is a well engineered structure sitting on a support system that is only as good as the ground it bears on. The chassis, the piers and the pads are all designed around an assumption about soil bearing capacity and about water not running through the support area. On raw acreage, nobody has verified either of those assumptions for you. You are the one making them.
Homeowners who put real effort into the pad and the drainage tend to have homes that stay level for a long time. Homeowners who set on whatever the dozer left flat tend to be reading articles about releveling within a few years.
Choosing where the home goes
Go high, not convenient
The most common mistake on rural land is siting the home where access is easiest rather than where the ground is best. Look for the high ground in the buildable area. Water runs downhill and collects in low spots, and a home in a low spot is a home with water under it every time it rains, regardless of how well the pad is built.
Read the drainage before you clear
Walk the property during or right after a heavy rain if you can. That single visit tells you more than any amount of dry weather inspection. Note where sheet flow travels, where water pools, where channels form, and how long it takes for things to drain. Then site the home out of those paths.
Know your ground
In this part of East Texas the answer varies. On the eastern timberland side of Anderson County and across Houston and Cherokee counties, the soils are typically deep, sandy and loamy, in the Fuquay, Kirvin and Darco group, with Darco being a very deep sand. On the western side of Anderson County the ground is claypan pasture, with a dense, slowly draining subsoil.
That difference should shape your prep. On sand, plan for pads that are generously sized and bearing on compacted material, and plan hard for erosion control. On claypan, plan for getting water away from the pad area, because slow drainage will keep the shallow layer your pads sit in saturated.
Clearing and what gets buried
Clearing timber creates a specific hazard: organic material left in the ground under the home. Stumps, root balls, brush piles pushed into a low spot and covered over, and buried slash all decompose. As they break down they lose volume, and the ground above them settles. Because decomposition takes years, this settlement often shows up long after the home is set, which makes it hard to attribute.
- Remove stumps and root balls from the pad area rather than burying them.
- Do not push brush or slash into the footprint and cover it.
- Strip topsoil and organic material from the pad area down to mineral soil.
- Keep the cleared pad area larger than the home footprint, with room to work.
Building the pad
Cut rather than fill where you can
A pad cut into undisturbed ground is more reliable than a pad built up out of fill. Fill settles unless it is placed and compacted correctly, and on rural jobs it very often is not. Where fill is unavoidable, it should go in in shallow lifts, each one compacted, rather than as one thick dumped layer.
Compaction is not optional on sand
Loose sand carries much less load than the same sand densely packed. Compacting the pad area is one of the highest value things you can do on a sandy site, and it is far cheaper before the home arrives than any repair afterward.
Crown the pad
The finished pad should be slightly higher in the middle than at the edges, and the ground should fall away from the home in every direction. Even a modest slope away from the perimeter keeps water from finding its way into the crawl area and pooling around footings.
Drainage details worth doing at setup
- Positive grade all around. Ground falling away from the home on all four sides, with no flat or reverse sections.
- Gutters and downspouts. On sandy ground, uncontrolled roof runoff is the single most reliable way to scour soil from beside your piers. Discharge well away from the perimeter, not at the skirting line.
- An interceptor swale upslope. If any part of the property drains toward the home, catch that water before it gets there.
- Driveway runoff. A compacted drive sheds water like a roof. Make sure it sheds away from the home rather than toward it.
- Septic and utility trenches. Backfilled trenches are preferential water paths. Do not run them toward or under the home footprint if it can be avoided.
- Ground vapor barrier. A barrier under the home reduces moisture in the crawl area, which protects the underbelly and the floor framing.
Piers, pads and anchors at setup
The installation should follow the manufacturer's setup instructions for your specific home and the applicable Texas installation standards. Beyond that, a few things are worth the buyer's attention on a sandy rural site:
- Pad sizing. Ask what size pads are being used and what soil bearing capacity that assumes. On loose sand, err large.
- Bearing surface. Pads should bear on compacted or undisturbed material, not on loose surface sand or uncompacted fill.
- Point loads. Fireplaces, garden tubs, kitchen islands and marriage line columns need their own support. Confirm they are accounted for.
- Anchor capacity for the soil. Anchor holding depends on the soil it is installed in. Loose sand generally requires more anchoring capacity than dense soil.
- Access. Leave a real access panel in the skirting, positioned where a technician can reach the plumbing and the pier lines.
Things acreage buyers underestimate
- Driveway construction. A soft drive costs you at delivery, at setup, and at every service call for the life of the home.
- Turning and setting room. A home has to be maneuvered into position. Trees left too close can force a compromise in where the home ends up sitting.
- Tree distance. Nice for shade, hard on the roof and skirting during storms, and they keep the crawl area damp.
- Future additions. A porch or a carport added later needs support of its own. Thinking about it at setup is easier than retrofitting.
- Erosion during the first year. Freshly disturbed ground with no vegetation moves in the first heavy rains. Get cover established quickly.
A short checklist before the home arrives
- Home sited on high ground, out of the drainage paths you observed.
- Pad area cleared of stumps, roots, brush and topsoil down to mineral soil.
- Pad cut rather than filled where possible, and compacted where fill was used.
- Pad crowned with grade falling away from the footprint in every direction.
- Interceptor swale in place if anything drains toward the site.
- Gutter plan decided, with discharge points well away from the perimeter.
- Pad sizing and anchor plan confirmed with the installer for your soil.
- Driveway built well enough to carry delivery and service traffic.
- Vapor barrier planned, and skirting with a usable access panel planned.
After the home is set
Check elevations again after the first full wet season. New pads take a little time to seat, and the first year is when any prep shortcuts announce themselves. Catching a small amount of movement early is a shim adjustment. Catching it after several years is a rebuild. If something does move, use the pattern to figure out the cause before you fix it: a single dropped pier on sand points to pad sizing or scour, while broad seasonal movement points to water sitting in the shallow layer under the home.