## How to Size Gutters & Downspouts

Half round and K-style gutters would be the two most frequent gutter types found on residential houses. Each gutter design comes in two dimensions and each has the capability to transfer a particular quantity of water from your roof. Correctly matching the size and style of a gutter to your house necessitates careful dimensions and exact calculations to ensure the gutters don’t float through heavy or prolonged periods of rain.

Set up an extension ladder from one border of your home’s roof. Be certain that the ladder extends at least three feet beyond its upper resting point against the roof edge. Place a torpedo level and tape measure in a tool pouch to keep your hands free. Climb the ladder, maintaining three points of contact at all times. For example, keep two feet and a hand or two hands and one foot on the ladder at all times.

Place the torpedo level on the roof together with the amount body sitting perpendicular to the roof peak. Adjust the amount until it reads degree. Hold an extended tape measure at the close of the level that isn’t touching the surface of the roof. Transfer the tape measure so that its blade is sitting right from the end of the degree. Measure the distance between the roof and the bottom of the level. The dimension will determine the pitch of the roof. For example, a distance of 6 inches would signify that the roof includes a 6-in-12-inch pitch.

Measure the length and width — distance from the eave to the peak of the roof — of one side of the roof. Multiply the 2 measurements to find the area of the roof section. For example, if the length of the roof section is 50 feet and the width is 25 feet, the area is 1,250 square feet. Determine the area of each roof section. When determining the area of a triangular hip roof, then use the formula: length times width divided by 2.

Locate the roof pitch — incline factor — for your pitch of your roof by consulting a roof pitch chart or using these values: For roofs involving horizontal and 3-in-12 in pitch, use a factor of 1. For 4-in-12 or 5-in-12, use 1.05. For 6-in-12 to 8-in-12, use 1.1. For 9-in-12 to 11-in-12, use 1.2. For 12-in-12, use 1.3.

Multiply the largest square footage from the corresponding roof pitch element. In the example, multiply 1,250 square feet from the corresponding roof factor of 1.1 for a drainage area of 1,375 square feet. Multiply the drainage area from the maximum rain for your area in inches per hour. For example, for the San Francisco area, you would multiply 1,375 square feet by 2.7 to get a entire drainage area of 3,713 adjusted square feet.

Compare the adjusted square footage to the two most frequent gutter types. K-style gutters possess the ability to move either 5,520 square feet for 5-inch gutters or 7,960 square feet for 6-inch gutters. Half-round gutters transfer less water and permit to get 2,500 square feet to get a 5-inch diameter or 3,840 square feet to get a 6-inch diameter gutter. For example, the 3,713 adjusted square feet in the previous example would allow you to use either a 5-inch K-style gutter or a 6-inch half-round gutter when installed with the typical pitch of 1/4 inch per 10 feet.

Decrease the necessary size of your gutters by installing more downspouts compared to normal spacing of one every 40 feet. The amount of additional downspouts needed to boost the gutters’ capacity will depend on the size of the downspout. For example, adding one 4-inch round downspout will raise the gutter capability by 1,255 square feet, and one 3-inch round downspout would boost capacity by 706 square feet. Rectangular downspouts move slightly less water, at 600 square feet for 2-by-3-inch or 1,200 square feet for a 3-by-4-inch downspout. Multiply the amount of downspouts by square footage of each downspout. For example, one 4-inch downspout would saturate 1,255 in the initial 3,713 and would reduce the drainage area to 2,538 square feet.

See related

## Modern Minimalism at a Multigenerational Home

When designing this house for a three-generation family, architect Joshua Nimmo developed a strategy to enhance the relationships between family members by providing smaller personal spaces around larger family ones, inside and outside. The courtyard with pool is the most significant; many of the rooms have been oriented toward it via big glass walls shaded by roof overhangs. It’s a classically modern one-story pavilion where connections — between family members and also to nature — are paramount.

The owners are still working out the interiors, so this tour concentrates on the design as a blank slate — prior to furnishings as well as other interior design elements will gradually complete the house. The photos nevertheless highlight the materials and surfaces that help shape the many different rooms and what happens inside them. The photos of the house at this point also prompt us to consider how to”finish” it. I have my thoughts. Which are yours?

at a Glance
Who lives here: A 3-generation family
Location:
Dallas
Size:
6,700 square feet; 5 bedrooms, 5 full baths, 2 half baths

NIMMO American Studio For Progressive Architecture

The house is fairly solid and introverted when viewed from the road to the south. A mirrored wall screens the garage on the left, and weathered steel gates provide access to front court on the right. The floating roof beyond the gates hints at the transparency of the house.

The house is above average in size at 6,700 square feet, but remember it does function three generations, and it is in keeping with homes in the region.

NIMMO American Studio For Progressive Architecture

The front court is a generous outdoor area that clearly and carefully produces a transition between the external world and the kingdom of the house. One walks along the grass on the concrete hardscape into the wood-paneled front door.

NIMMO American Studio For Progressive Architecture

Weathered steel doors rally in the middle and seem to float over the concrete.

NIMMO American Studio For Progressive Architecture

The courtyard with pool is a really large space within view of some of the personal spaces and all the shared family spaces. From left to right we see the master suite, then the expansive living area and finally a sign of the kitchen at the far right.

The pool, generous roof overhang and glass walls provide a clear north-south directionality into the house. (We are looking underwater, so north is to the left and south is to the right.)

NIMMO American Studio For Progressive Architecture

Given the warmth of Dallas, the pool is a wonderful amenity for cooling off, and the roof overhang is essential for shading the outdoor area (to make it really usable) and the glass wall, which would otherwise admit too much afternoon sunshine into the inside. Further shading comes in the tall sycamore and other trees around the west side.

NIMMO American Studio For Progressive Architecture

This is my preferred view of the house, for it reveals a straight shot through the inside from the outdoor area by the master suite to the front court, as well as the layering of four parallel strips: inside route, outdoor area below the roof, pool and grass. We could even see into the grandparents’ suite, which is located at the end of the pool.

NIMMO American Studio For Progressive Architecture

Here is a similar opinion, but at nighttime, showing the way the master bundle pops out into the footprint of the pool.

NIMMO American Studio For Progressive Architecture

The covered outdoor area totals approximately 1,000 square feet and raises the area dedicated to solar panels onto the roof.

NIMMO American Studio For Progressive Architecture

In this photo we are looking roughly from the kitchen toward the formal dining and living room, and at the fireplace that separates it from the casual recreation space beyond. To the right of the fireplace are glass doors leading to a small court that provides a location for family members to be alone outside.

Materials are few and minimally detailed: The fireplace is walnut, like the exterior; the floors are bleached oak; and the timber wall on the right is created out of walnut veneer panels.

NIMMO American Studio For Progressive Architecture

In the fireplace we get a direct view into the courtyard and pool. The west sun is streaming through the glass walls, but it is fairly low under the massive overhang, meaning the glass and interior are shaded from most of the afternoon sun and the sun will shortly be setting.

NIMMO American Studio For Progressive Architecture

A nice detail are available at the firewood storage on the side of the limestone hearth; this picture looks toward the walnut-covered walls we found before. Since the residence is at Dallas, the fireplace will not be used too often, but Nimmo integrated a geothermal HVAC system to ensure that even in the warm months, the electricity use is going to probably be kept to a minimal.

NIMMO American Studio For Progressive Architecture

On the opposite side of the fireplace (confronting the small recreation rooms) is some tall, narrow storage behind darker rock doorways.

NIMMO American Studio For Progressive Architecture

The huge kitchen includes white flush closets and Calcutta Danby rock for the countertops and the backsplash.

NIMMO American Studio For Progressive Architecture

The exact same bright white surfaces can be found at the home office, adjacent to the master bedroom. As from the kitchen, panels expand into the ceiling to cover the entire wall and make a consistent appearance.

NIMMO American Studio For Progressive Architecture

The finishes and details inside the house are resolutely modern and minimalist (notice the reveal at the wall foundation that continues up and above the opening), but they are divided by touches like this barn door created with reclaimed wood.

Credit ought to be awarded to Rick Fontenot from Constructive General Contractors, who built those modern, minimalist details that are so much more challenging to pull off than they appear.

NIMMO American Studio For Progressive Architecture

The timber walls and Calcutta Danby vanity actually stand out from the powder room, but I am attracted to the narrow mirror.

The slender proportion of the mirror connects it to other parts of the house — the firewood storage, the narrow doorways set in the other side of the fireplace, the walnut panels, the barn door, even the pool if we flip it vertically — creating an architectural theme throughout the house that alleviates the predominantly mild and horizontal surfaces.

If I were fortunate enough to be charged with fitting this out inside, these verticals are something I’d pick up on, besides finding ways to reinforce the orientation of the spaces into the courtyard.

How can you work with the design to complete this home’s inside?

See related