Buying a house with a sagging roof
A sagging roof is a structural problem, not a shingle problem. Get the cause named before your deadline, then ask for the repair or its price.
Updated · By 
Ben Sikes
Should you buy a house with a sagging roof?
You can buy a house with a sagging roof once you know why it sags and what the fix costs. A sag is a structural problem, not a shingle problem. Book a structural engineer before your inspection deadline to name the cause. Then ask the seller for the repair, or a credit sized to a contractor's written bid.
Key takeaways
- Truss repair is the costliest row in the table and usually requires an engineer's stamp plus a permit.
- A truss roof calls for a structural engineer, while a conventional rafter roof can sometimes go to a qualified contractor.
- Cracking or bowing on the walls can point to the same framing problem, so show those report lines to whoever evaluates the roof.
How much does it cost to fix a sagging roof?
Prices differ mostly by what the fix involves. Use the row that matches the engineer's finding until a contractor bids on the plan.
| Source | What the figure covers | Cost |
|---|---|---|
| Today's Homeowner | Sag from localized framing issues | $750 to $1,500 |
| Econo Roofing (local, Stanislaus and Merced counties, California) | Sagging roof repair, structural, depending on cause and extent | $2,000 to $7,000+ |
| Econo Roofing (same page) | Local sag from decking water damage | $2,000 to $3,500 |
| Econo Roofing (same page) | Rafter sistering, which adds support boards to weakened rafters; price depends on how many rafters | $2,500 to $5,000 |
| Econo Roofing (same page) | Truss repair, which usually requires an engineer's stamp plus a permit | $5,000 to $15,000+ |
| Cobex Construction Group (local, Sacramento, California) | Major repairs, including sagging roof reinforcement | $3,000 to $8,000+ |
A worked example for weak rafters, before any bids arrive: the engineer's visit, Econo's Central Valley sistering range and its local permit estimate of $150 to $500 come to $3,000 to $6,300 ($350 + $2,500 + $150 at the low end, $800 + $5,000 + $500 at the high end). Swap in the engineer's fee, the contractor's bid and your building department's permit fee as they arrive.
Kept prices every line of an inspection report for $79, usually under 4 hours, and marks the ones that need a professional's quote.
How serious is a sagging roof?
Treat it as serious until someone qualified says otherwise. The International Association of Certified Home Inspectors (InterNACHI) warns that sagging rafters or inadequate rafter ties "can cause the ridge to sag and the exterior walls to bow out."
Your inspector only sees what's visible. Where framing is hidden, inspectors look for signs such as sagging, unevenness, or cracking on the walls, inside or out. If your report notes those too, show them to whoever evaluates the roof.
What should you do if your roof is sagging?
Get the framing looked at before your deadline, not after closing. InterNACHI tells inspectors that for truss roofs, "you should recommend a structural engineer because most of the defects related to trusses require calculations." For conventional rafter roofs, a qualified contractor can sometimes handle it. If you're not sure which you have, call the engineer.
Call today. Good structural engineers are busy and may not be able to respond quickly. A structural engineer's home inspection runs $350 to $800, per Today's Homeowner. Ask for a written repair plan a contractor can bid on.
How to get repair estimates during the inspection period covers getting bids back in time.
Does a sagging roof need to be replaced?
Not always. Today's Homeowner says a sag caused by localized framing issues can be fixed, while more severe sagging may need a bigger structural repair.
The repair depends on the cause: decking water damage, weakened rafters or a failing truss. The table prices each.
The engineer's visit tells you which one you have.
What should you ask the seller for?
Ask for the repair, done by a licensed contractor to the engineer's plan before closing. Or ask for a credit sized to the contractor's bid, and hire your own after closing.
If the seller does the work, ask for the engineer's plan, the contractor's invoice and any permit sign-off before closing. That lets you check the work matches the plan.
What to ask for after a home inspection covers where this line sits in your list. The buyer repair request letter template gives you the wording.
What if the seller says no?
You have three moves:
- Switch the ask. If they refused the work, offer to take cash and hire your own contractor. If they refused cash, ask for the work.
- Trim the rest of your list. Keep the roof framing and drop the cosmetic lines.
- Walk away if no one can price the fix before your deadline. When to walk away after a home inspection walks through that call.
Your contract sets the deadline and how you can cancel, so confirm both with your agent. Other roof lines are in roof findings on an inspection report.
Will insurance cover a sagging roof?
Don't count on it. Liberty Mutual says roof damage from general wear and tear or lack of proper home maintenance typically won't be covered. Ask your insurance agent before your deadline whether a documented sag affects the policy you'd buy.
How much roof sag is acceptable?
The International Residential Code limits how far new framing may bend under its maximum design load, per the American Wood Council. It sets no number for an old roof; the engineer measures this.
How do I know what my whole list is worth?
The engineer and a contractor cover the sag, and the rest of your list needs numbers too.
If the sag is one line in a long report, upload your inspection report to Kept and spend your remaining days on the engineer.
Sources
- InterNACHI, Evaluating Structural Framing
- InterNACHI, Structural Problems: Recommend a Contractor or Engineer?
- Today's Homeowner, How Much Does Roof Repair Cost?
- Today's Homeowner, How Much Does a Structural Engineer Cost?
- Econo Roofing, Roof Repair Cost in California
- Cobex Construction Group, How Much Does It Cost to Repair a Roof?
- American Wood Council, Tutorial for Understanding Loads and Using Span Tables
- Liberty Mutual, What Is Not Covered by Homeowners Insurance?
Cost figures are modeled from public wage and materials data unless a line says observed. Kept is accountable for the numbers on this page, and corrections go to support@usekept.com. How we price.