Buying a used knock-down house: what to check
Contents
In short
- See the unit in person in daylight, and after rain if you can.
- The costliest repairs are rust on the base frame and where the frame meets the floor.
- Work out the real price: purchase, lifting, transport, repairs and new supports.
- Fresh paint can hide problems, so look under the floor and on the roof.
What to ask before you go
The seller's answers can rule out units that are not worth the trip. Ask in a chat so you keep a record.
- What was it used for: housing, an office or a construction site?
- Where has it been? Near the sea or a chemical plant, rust may be worse.
- When was it made, and how many times has it been moved?
- What is the real inside size?
- Can you send photos of the underside, roof and electrical panel?
- Does the price include lifting it onto the truck?
What to inspect yourself
Bring a torch, tape measure, screwdriver and spirit level. This table runs from the hardest repairs to the easier ones.
| Where | What to look for | If you find it |
|---|---|---|
| Base frame | Rust, cracked welds, thinning steel | Usually means cutting and re-welding, which is costly |
| Floor | Walk the whole room for soft spots. Check for swollen or damp edges. | Water may be getting under the floor, or the floor frame is damaged |
| Roof | Yellowed or lifted sealant, rust along joints | It may leak in the rainy season |
| Ceiling and walls | Water stains, swollen panels, peeling, patches | Trace where water gets in, not just the mark inside |
| Doors and windows | Open every one. Check for sticking or gaps of light. | The frame may be twisted, or the unit not level |
| Electrics | Panel, brittle cables, every socket, earthing | Allow for some rewiring |
| Bathroom | Leak marks around the toilet, pipes under the floor, smells | Ask whether pipes were cut when it was moved |
Check whether it is twisted
Put a level on the floor in several places, and try a marble to see which way it rolls. If the unit sits on sloping ground, check the doors and wall corners as well. Once sold, it has to be lifted, and a twisted frame can open new leaks. Ask where the lifting points are and whether they are sound.
Work out the real price
The purchase price is only part of it. Add these before comparing with a new unit.
- Removal: disconnecting pipes and power, and unfixing anything attached.
- Lifting and transport: you need lifting at both the pickup and the new site.
- Repairs: roof, floor, electrics and paint.
- Work at the new site: supports, water, power and drainage.
For budgeting, see What kind of knock-down house can ฿100,000 buy?
Agreeing the sale
- Keep photos and video of its real condition.
- Write down what comes with it, such as air conditioning, furniture and water tanks.
- State who is responsible for removal, lifting and damage in transit.
- Agree a removal date, and any site rent if you are late.
- Get a receipt or other proof of sale.
Frequently asked questions
Does fresh paint mean good condition?
Not necessarily. New paint can cover rust or repairs. Look under the floor, at the bottom corners of walls and around windows, where paint often does not reach.
Can I buy without seeing it?
We do not recommend it. If you must, ask for one unbroken video of the underside, roof and electrical panel, or pay a local builder to inspect it.
Is used always better value than new?
Not always. With moving and repairs, the cost may come close to new. Compare the real, ready-to-use cost of both.
Do used units have a warranty?
It depends on the seller. If a dealer has refurbished the unit, ask what is covered and for how long, and get it in writing.