Guides
Construction type and rates: frame, masonry and more
How insurers classify frame, masonry veneer and masonry homes, why walls matter for fire and wind, and why a brick house is not always rated as brick.
Insurers sort houses by what the exterior walls are made of, because wood burns and brick generally does not, and because masonry walls tend to hold up better in high wind. The result is a construction class, usually frame, masonry veneer or masonry, and it is one of the factors multiplied into your rate. The NAIC's consumer guidance says frame houses usually cost more to insure than brick ones, but no one can give you a standard percentage: each insurer files its own factors.
The classes insurers use
Homeowners rating plans use a short list, and the pattern is common across carriers. As one example, the North Carolina underwriting guide of Homeowners of America (Homeowners of America) defines four classes:
| Class | What it means |
|---|---|
| Frame | Exterior walls of wood or other combustible construction, including siding over a wood frame and stucco on wood |
| Masonry veneer | Walls built of combustible framing and faced with brick or stone |
| Masonry | Walls of masonry materials such as brick, concrete block or adobe, with combustible floors and roof |
| Mixed | Classed as frame when frame walls, gables included, exceed 33 1/3% of total exterior wall area, and as masonry otherwise |
Siding does not change the class. A wood-framed house wearing vinyl or aluminum siding is still frame. Stucco over a wood frame is frame; stucco over concrete block is masonry. The test is what the wall is built of behind the finish. Your insurer's own manual and your state's filed rules control the exact definitions, and some plans add a separate class for fire-resistive construction such as poured concrete or steel, which almost no single-family houses meet.
Why the six-class commercial list does not apply to you
If you search the topic, you will find the six ISO building construction categories: frame, joisted masonry, noncombustible, masonry noncombustible, modified fire resistive and fire resistive. According to IRMI's summary of ISO's Commercial Lines Manual, those are numbered 1 through 6 and describe commercial buildings. They also treat brick veneer over a wooden frame as Frame, while many homeowners plans give masonry veneer a class of its own. If an agent or an article quotes the six-class list for your house, ask whether the carrier rates your home on a homeowners table. See construction class for the glossary definition.
Why walls matter to the insurer
Fire
The older reasoning is simple. A fire that starts in a frame house has wood walls, wood floors and a wood roof to feed on. A masonry house with combustible floors and roof still burns inside, but the walls themselves do not feed the fire. That is the general reasoning behind frame costing more to insure.
Construction type interacts with Fire protection class (ISO PPC) and your rate. A frame house a long way from a hydrant and a staffed station is the combination insurers are least comfortable with, and the two factors compound in the rate.
Wind
For wind, masonry has a record to point to. Verisk's storm analysis for Hurricane Hermine (2016) noted that masonry houses are better able to withstand high winds than wood ones, and gave the reason: masonry walls run full height, with the wood floors and roof framed into them, which produces continuous exterior walls and a strong overall frame.
The counterpoint matters, though. A wood-frame house built to a modern code with a continuous load path, from roof to walls to foundation, can perform well too. In coastal states the better predictor of damage is often the roof covering, roof-to-wall connections and opening protection. That is why wind mitigation features, not wall material, earn most of the wind discounts; see wind mitigation inspections and discounts.
Wildfire
In wildfire country the siding and the details matter more than the class label. California's Safer from Wildfires rule, 10 CCR §2644.9, requires insurers whose rating plans use wildfire risk to give credit for a Class A roof, enclosed eaves, ember-resistant vents, multipane windows (or shutters) and at least 6 inches of noncombustible clearance at the bottom of exterior walls (California Department of Insurance). Notice that none of that is "frame or brick." A brick house with a wood shake roof and open eaves can be a worse wildfire risk than a frame house with fiber-cement siding and a Class A roof. home hardening for wildfire and insurance discounts goes through the details.
The mistakes that cost people
Calling a veneer house a brick house. Many houses described as brick are a single layer of brick facing over a wood frame. If the application says masonry and the structure is veneer, the quote is too low. An inspection, an appraisal or a claim adjuster who sees the wall cross-section can lead to a re-rating, or in a bad case a dispute over what was represented. Check with the builder's documents, the original plans or the county's records.
Forgetting what changed. An addition, a rebuilt porch or a second story may have been built with different materials from the original house. If frame walls end up making up more than a third of the exterior, the mixed rule can class the whole house as frame.
Assuming masonry always means a lower premium. The construction factor applies to the rate per $1,000 of dwelling coverage. But the dwelling limit itself should follow the cost to rebuild, and solid masonry usually costs more to rebuild than frame. A lower rate on a bigger limit can leave you paying about the same, or more. Use the home replacement cost estimator and How much dwelling coverage do I need? to set the limit before you compare construction effects.
A hypothetical: two houses, one street
These numbers are invented to show how the two effects work against each other. Actual factors vary by insurer and state.
Say two identical 2,400-square-foot houses stand on the same street, one frame and one solid brick. A rating plan shows a construction factor of 1.00 for frame and 0.88 for masonry. Rebuilding the brick house costs 8% more, so its dwelling limit is $432,000 against $400,000 for the frame house. Using a hypothetical base rate of $4.50 per $1,000 of coverage:
- Frame: $400,000 ÷ 1,000 × $4.50 × 1.00 = $1,800
- Masonry: $432,000 ÷ 1,000 × $4.50 × 0.88 = $1,711
The brick house is cheaper, but only by about 5%, not the 12% the factor suggests. If its wall factor had been 0.95 instead, the brick house would be $1,847 and cost more to insure than the frame one. The lesson is to compare quotes at the correct dwelling limit for each construction, not at an identical dollar amount.
What to do
- Look at your declarations page and quote. Find the construction line (frame, masonry veneer, masonry) and confirm it matches your house. your declarations page explained, line by line shows where the rating fields sit.
- Pull the paper. Original plans, permit records, builder specifications and photographs from a renovation can prove a wall's makeup if the insurer's data is wrong.
- Report changes. Tell your agent about additions, siding changes and re-roofing; they can shift the class and the roof factor.
- Ask which perils the factor touches. Some plans apply construction type to fire only; others apply it to wind and hail as well. A masonry home in hail country may not see the credit it expects.
- Compare insurers. Each one sets its own construction factors, so the same house sits in a different place at each company. what affects your homeowners insurance rate explains why factors multiply.
Log homes, manufactured homes and unusual builds (shipping containers, domes, steel buildings) often fall outside the standard classes and are underwritten individually. insuring a log home and mobile and manufactured home insurance cover those.
Key takeaways
- Insurers classify homes as frame, masonry veneer or masonry (and sometimes fire-resistive) by what the walls are built of, not by the siding; the NAIC says frame houses usually cost more to insure than brick.
- Brick veneer over a wood frame is not solid masonry in most homeowners rating plans, so confirm how your quote classifies the house.
- Wall type affects fire and wind pricing, but roof covering, roof connections, openings and wildfire details often matter more than the label.
- A masonry discount can be offset by a higher rebuilding cost and dwelling limit, so compare quotes at the correct limit for each construction.
- The six ISO construction classes you may find online are commercial classes; ask your insurer which table rates your home.