The City of Albuquerque sets its own minimum ground snow load, by elevation, through the Building Safety Division. This guide explains what that means for a roof, how to get the value for an address, and why this site does not state a number.
Key takeaways
- The City of Albuquerque sets the ground snow load through its Building Safety Division, not a national map alone.
- The value depends on elevation, so two addresses a few miles apart can have different figures.
- A third-party guide says the City's value can exceed the ASCE 7-16 map baseline. The numeric value was not confirmed for this site.
- A ground value is converted to a roof load using the roof's shape, exposure and slope. That step is done by the roofer or an engineer.
- Ask the City for the figure in writing for the address before a replacement is designed.
Why does a roof need a snow load at all?
Because a roof has to carry the weight of snow the building is expected to see, and the framing is sized for that weight when it is built or re-roofed.
A roof carries its own weight, the covering and the load of any snow or ice that settles on it. The framing is designed for a particular combination, and if the design load is lower than the one now required, the framing can deflect, crack or fail under it. Most of the time the danger is slow: sagging rafters, a ridge that drops and sheathing that splits along a span.
Replacing a roof is the moment the question is cheapest to answer. A new covering is heavier or lighter than the old one, the decking may be renewed, and the designer has to know the load before the materials are ordered.
- The load the framing was designed for
- The load the City now requires at the address
- The weight of the new covering and any added layer
Who sets the number, and how?
The City of Albuquerque, through the Building Safety Division. The FACTS sheet records that the City sets the minimum ground snow load by elevation.
The FACTS sheet records that the City sets its own minimum ground snow load through the Albuquerque Building Safety Division, and that the value is based on elevation. That is the City's rule, and it is the figure a roofer should use for a City address. A national map may be a useful reference, but it is not the City's number.
Elevation matters because the City's value changes with the height of the ground. The same street can have different figures at different points, so the figure is taken for the address and not for the neighbourhood name.
- The City sets the minimum ground value
- The figure depends on elevation at the address
- A national map is a reference, not the City's rule
How do you get the figure for an address?
Ask the Building Safety Division for the minimum ground snow load at the address, and write down the date, the reply and the name of the person who gave it.
Give the City the street address, not just the neighbourhood or the town. The reply should state the ground value and the date, and the record should be kept with the roof file. A roofer who is designing a replacement will need the same figure, and it is easier to have it on paper before the design begins.
If the City's answer is unclear, ask the question in writing. A clear written reply is more useful than a telephone summary, because the design relies on the number and the design may be checked later.
- Give the full street address to the City
- Record the reply, the date and the name of the person
- Keep the figure with the roof file
What does a roofer do with the number?
Converts the ground value to a roof load for the shape and exposure of the roof, then checks the framing against that load.
The ground value is not the load on the roof. The roof load is worked out from the ground figure and from factors that depend on the roof's shape, how exposed it is and how steep its slope is. A flat roof can carry a different load from a steep one using the same ground value, so the conversion is part of the design.
The framing is then checked against the roof load. A roofer can measure the rafters, the joists and the spacing in the attic, and an engineer can check the calculation where the framing is short or the design is unusual. The result is written down before the covering is ordered.
- Convert the ground value to a roof load
- Measure the framing in the attic
- Bring in an engineer where the framing is short
What if the framing is short?
Strengthen it to the designed load before the new covering goes on. Do not cover a roof that cannot carry the load it is required to carry.
Short framing can usually be strengthened, but the strengthening has to be designed for the load and checked by the roofer or an engineer. The work is quoted as its own line, so the homeowner sees what it costs. A roof that is covered without that step carries a risk that cannot be seen from inside the house.
Where the framing is found short, the record should say so, name the areas affected and explain the options. That record is useful later for a sale, a claim or an insurer's question about the roof's condition.
- Strengthening designed for the stated load
- Each affected area named in the record
- Options written out before work begins
How does elevation change the figure?
The City's value depends on the height of the ground at the address, so two addresses can have different figures even on the same street.
Albuquerque sits on a long slope that rises toward the Sandia foothills, and the ground height changes across the city and the wider service area. The City's rule uses elevation, which means the figure is set by where the address sits, not by its neighbourhood or its postal code. For a homeowner that is the most useful thing to remember: the number belongs to the address.
A roofer working in the outlying towns, such as those in the foothills, may find the elevation there is higher than in the city centre. The same rule applies, and the City or the county office that governs the address gives the figure for it.
- The figure belongs to the address
- Higher ground can carry a different value
- Ask for the value for each address separately
What questions should a homeowner put to the City?
The address, the value for the address, the date of the value, whether it is ground or roof load, and whether the value must be used for a re-roof.
A short written question is the most reliable route. Give the full address and ask for the minimum ground snow load that applies to it. Ask for the date the value was given and whether the figure is a ground value or a roof load. Ask whether the City requires the value to be used for a re-roof, and whether a design is needed to show it was used.
Keep the reply. A reply that gives the figure and the date is far more useful later than a remembered phone call, and it is the document a roofer will need for the design.
- The full address
- Ground or roof load, stated
- Whether a re-roof must design to it
What about a flat roof and its snow load?
A flat roof carries the load over its whole surface, and any ponding adds to it, so drainage and the load are linked. The check must cover both.
On a flat roof the snow load and the drainage are connected. Snow that is not cleared, and water that stands in a basin, both add weight, and a basin that deepens over several seasons adds more. A flat roof that is designed to the City's value but drains poorly is not safe in the way the design assumes, so the drainage check belongs in the snow load question.
Ask the roofer to check the drains and the low points at the same visit as the framing. A roof that is designed to carry the load but has a drain sitting above its low point has a problem the design alone will not solve.
- Drainage and load are linked on a flat roof
- Check the low points during the framing check
- Ponding adds weight over time
What should a roof record keep about the load?
The City's value and its date, the framing measurements, the design load used, the engineer's note if one was needed and the strengthening lines if any were added.
A roof record should carry the load in a form that a future roofer, buyer or insurer can read. Keep the City's value with its date, the framing sizes and spacing, the design load used for the replacement and any engineer's note. If strengthening was added, keep its drawing or its scope line with the record.
A record that is clear about the load is one of the most useful documents a homeowner can hold. It answers the question before it is asked, and it saves a later inspector from measuring the attic again.
- The City's value and its date
- The framing sizes, spacing and design load used
- Any engineer's note and strengthening scope
Frequently asked questions
Does this guide give the snow load for my address?
No. The City sets the value, and this site did not confirm the numeric figure. Ask the City's Building Safety Division for the value for your address.
Is the snow load the same across the city?
Not necessarily. The value depends on elevation, so the figure is taken for each address.
Does the snow load matter for a flat roof?
Yes. A flat roof carries the load over its whole surface, and ponding adds to it. The conversion accounts for the roof's shape.
Who pays for the check?
The roofer quotes the check as part of the scope or as a separate line, and the written quote shows which.
Sources
This guide is general information for Bernalillo County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.