How to Estimate Vinyl Siding

Vinyl siding

Most homes build before the 1950 s were sided with brick, stucco or wood. Stucco and brick required the least maintenance of the three but after time brick needed re-pointing and stucco needed to be repaired.

Aluminum siding was a breakthrough in building supplies because it gave homeowners these wonderful perks:

  • Little or no maintenance
  • Came in a variety of colors
  • Could be installed by professionals in a couple of days
  • Water repellent.

The age of aluminum siding began wane not more than a decade after it was introduced. Not only did the coloring of the aluminum fade it was easily dented and, in many parts of the country, could be beaten up by a hailstorm. This is when vinyl siding made its debut and houses have never been the same.

Measuring is Not Magic

Whether the house will be sided with vinyl, wood, steel or stucco one main element is constant in all of the siding jobs: calculating the area to be covered. Before an installation can take place the contractor needs to know the amount of material needed and, for the most part, this number directly determines the labor costs.

The best way to measure the exterior of a home is by dividing the home into geometric shapes. For example, the walls up to the gables can be measured as rectangles and the gable ends as triangles. Then it is just matter of finding the area:

Rectangle: Height X Width

Triangle: Height X Width then divide by 2


1. Measuring Materials: Buy a pad of graph paper and have a few sharp pencils ready. It always pays to have diagrams drawn as close to scale as possible. A good tape measure will work but for the best results get a 100-foot land surveying tape measure. This will save having to measure in sections. Although, a stiff metal tape works best for vertical measurements.

2. One Side at a Time: Begin measuring at the front. When the two measurements have been taken draw in the shape. Also, measure the windows because J-molding and, if needed, cladding labor for the frames may be needed.

3. Obstacles: Draw in all obstacles like pipe stacks, electrical masts and shutters. All these will have to be moved or moved aside.

4. Hidden Walls: Areas that are hidden from frontal view but visible on the side, like alcoves for doors, are called hidden walls. They can either be noted or drawn in a 3-D format but make sure they are added in.

5. Addition: Add all the triangles and squares for each page and write them down. Now add the totals of all the walls. This will be the square footage of all the walls and can be used to calculate the amount of flat siding needed. This number will also work for a complete stucco job because no other pieces are needed such as corner pieces.

6. Linear Numbers: For soffits, gutters, downspouts, corner pieces, inner-corner pieces, fascia and starter strips the linear footage is needed. Go back to the diagrams and figure these out for each page. When this is done look at the building supply catalogue and see what lengths these pieces are sold. For example, if a corner is nine feet high then one piece of ten-foot vinyl corner is needed. J-channel goes along the top of the siding and around windows and doors. F-molding holds in the soffits on each side so this amount has to be doubled.

7. Add the Pieces: To get the amount of materials needed begin with the biggest portion: the area. If the area is 1425 square feet add another 10% for wastage so this would be 1567.50. Now, if the cost of the siding is $75 per 100 foot square then the cost is 15.68 times $75 = $1175.63. This is the total of the flat siding. If there are four outside corners at $10 each this would be $40 and two inside corner at $8 would be $16. Do this for the gutters, fascia, soffits, downspouts and starter strips. Now add the starter strip, F-moldings and J-channel.

8. Other Materials: Siding is best put on a completely flat surface and for this there is a wall leveling product made from foam sandwiched between two sheets of thin aluminum. This will also add an R-value to the home and help seal it. A 3/8-inch wall leveling product will add about $350 to the project. Nails will be needed for the fascia and siding. The building supply place will calculate the amount of nails based on the square footage.

Although it seems like a tedious job it will give each homeowner a rough estimate and a basis to evaluate quotes from a professional. Take it one step at a time and it will make sense.

For best results for a siding job consult our Contractor Directory or simply post your project online and get some free estimates.

Posted by: Kim Kinrade
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