Rules
Part of Historic Home Restoration Mistakes to Avoid
Which hiring questions keep homeowners from repeating old mistakes?
Screening questions that reveal whether a contractor will use methods that damage old buildings, with the answers that should end the conversation.
What to take away
- Ask about method, not experience. Everybody has experience; not everybody has a method they can describe.
- The most useful questions have a wrong answer that is easy to recognize.
- Any proposal to clean, strip or coat a surface should include a test area before the main work.
- A contractor who has taken free federal training in preservation standards is telling you something about how they work.
These questions exist to filter, not to interrogate. Most take under a minute, and the answers sort candidates quickly.
Six questions with recognizable wrong answers
| Question | Answer that should worry you |
|---|---|
| How would you clean this masonry? | Sandblast it, or pressure wash it |
| What mortar mix will you use? | Whatever we always use, or standard cement |
| Do you seal masonry after repointing? | Yes, always |
| How do you strip exterior paint? | Take it back to bare wood everywhere |
| What do you do with removed original material? | Skip it |
| Will you do a test area first? | Not needed, we know this product |
None of these are trick questions. They separate firms with a documented method from firms with a habit.
Good vs Poor Answers
Good answer
- Masonry cleaning
- Assess brick first
- Mortar mix
- Match existing mortar
- Sealing
- Only if needed
- Paint stripping
- Selective removal
- Removed material
- Preserve and document
- Test area
- Required first
Poor answer
- Masonry cleaning
- Sandblast or pressure wash
- Mortar mix
- Standard cement
- Sealing
- Yes, always
- Paint stripping
- Bare wood everywhere
- Removed material
- Skip it
- Test area
- Not needed
Listen for how the answer is framed as much as what it says. A good answer starts with the building: what the brick is, what the existing mortar looks like, how weathered the surface already is. A poor answer starts with the product, because the product was chosen before anyone looked at your wall.
That order of reasoning is the most reliable signal in the whole conversation, and it takes no technical knowledge to hear. It works on suppliers too, where asking whether a patching compound is harder than the original tells you which market they sell into.
Insist on a test area
Any surface treatment should start with a small trial in an inconspicuous place, assessed after full cure.
That is standard in institutional preservation work, written into the procedures. The federal buildings service specification for removing graffiti from historic masonry is one example. Graffiti removal is where urgency pushes people toward the harshest product on an untested surface.
The test does two things. It shows whether the method works, and it shows what the method does to the substrate. The principle scales from surfaces to whole components, where one window repaired properly before the rest are ordered settles cost and feasibility together.
Ask what training they have had
Preservation training is available free, and firms that seek it out tend to work differently. The Park Service runs an online program covering the treatment standards and their application, listed on its training and webinar page. Asking whether anyone at the firm has done any is not a credential check; it is a question about curiosity.
A good answer might be that they have not, but that they work from the briefs. A poor answer treats the whole idea as bureaucracy.
Put the answers in the contract
Whatever method is agreed, write it into the scope: the cleaning method and pressure limits, the mortar mix and joint profile, the paint removal method, the test area requirement, and the handling of removed original material. Verbal agreement about method is worth nothing once a crew with a pressure washer is on site.
The underlying catalog of damaging methods is in the mistakes that damage old houses, and the general set of contractor questions is in our restoration hiring questions.
