FOUNDATION LAYOUT Home Position Property corners and property lines should be identified and proven, especially where the home is at or close to a set back distance. Setbacks distances must be obtained for the parcel property lines. The home should be placed as illustrated on the approved plot plan included with the permits and approved plans. For non-concrete foundation installations (soft set), it is important to locate and string property lines. If you find a property line that is obstructed by fences, vegetation and other obstacles, measure the setback distance from the property line corner pins and place a string line for the setback parallel to the property line. For instance, if the setback is 5’ from the side yard and there is a fence straddling the line, measure 5’ if from each of the two corner pins and string line the new points; this is the setback line. For concrete foundation installations, the permit card should be signed off at the first inspection as items “property setbacks” and “foundation footings and forms”. It is important to prove the setbacks to ensure the foundation is correctly placed. The position of the home must be checked against property line set backs, septic tank & leach field set backs, and other concerns that should be discovered in the planning process. Cut vegetation from lot and grade or level lot as needed for the foundation system and home requirements. Keep in mind a minimum chassis clearance of 12” from the ground is required but 18” is usually needed for heat duct clearance. When considering building on a sloped lot, be aware that many standard foundation plans are limited to a maximum bottom floor height of 36”, so be aware of any plan restrictions that may cause concern. Floor heights above 36” at the bottom may require additional engineering. Some jurisdictions and plans limit roof height. Errors It is mandatory that you set up a frame of mind to find the errors you will make as you go through the layout process. Failing to check and re check your work will likely result in errors. If you are too sure of yourself you will likely pass up the double check and find after the home arrives that the foundation and home do not match. The most talented will error a number of times on a project like this and you must keep an eye open for those errors before it is too late and you are embarrassed or financially hurt. Take your time and be careful of the help you use. Tape measures Tape measures come in many types and varieties. For a manufactured home layout I recommend using only steel or steel lined tape measures. The typical nylon tapes stretch considerably and must be used at a certain weight tension to be reasonably accurate. Steel does not stretch and can give nearly exact measurements.

Layout methods I have experimented with many types of layout procedures including using a transit, laser, adjusting parallel strings and finally using proven triangulation with tape measures. Unless you have a very high quality transit, it will likely give you an imprecise angle and be very time consuming to work. Lasers are pretty accurate but take time to set up and perhaps a receiver to pick up the beam on a sunny day. Both laser and transit work for finding points of the building but are difficult for transferring the points to a perimeter layout. Parallel strings takes time but can accomplish the task. My time tested favorite is triangulation with tape measures. Though I learned the skill in high school geometry class and have performed it many times by hand, I now use a construction calculator with the function built in and designed for inches and feet. The calculator uses the function for roof pitch, so the useful function buttons are rise, run and diagonal, however, when the triangle is pictured on its side, you have the making of a good rectangle divided diagonally. It is as simple as inputting the rise (width), run (length) and diagonal. When I layout a home, I first locate a pair of critical corners on the lot, tested for set back or as needed, then transfer the marks away to a larger layout that is 3’or 5’ larger in all dimensions or as practical. By doing this, I have proven corner hubs which are not affected during excavation. I can prove square easily with triangulation. I can measure along the sides for home batter board set up and all goes quite well and quickly once you have practiced. The layouts come out as perfectly as possible and are survey quality. Triangulation layout Foundations are to be built to the expected final dimensions of the home structure, so have a verified perimeter drawing of the home, which is the framing dimension not including the marriage gaps that will occur. The average home is a basic rectangle and we will concentrate on this type of set up. Some homes have offset walls and ends that complicate the layout. Generally it works well to start with a basic rectangle of the largest dimensions of the unit. First, locate two critical corners of the home adjusted for setback and any other concerns. Next, transfer the corners out 3’ (I will use 3’ offset for this example) for the beginning of the offset layout and extend them 3’ in each direction so the layout is a total of 6’ longer than the home. A 60’ home will equal 66’ for layout hub points. The hubs can be wood survey hubs of 2x2 with a driving point. I like to use a small square of plywood and spike it down on the corners; this gives a large area in which to locate a corner pin. After locating the first two layout corners, the third corner must be triangulated. The long side squared plus the short side squared equal the diagonal squared. For instance 60’+6’ =66’ 66’x66’ equals 4356. This unit is 27’ wide, add 6’ and multiply 33’x33’ equals 1089. Next add the 4356 and the 1089 equaling 5445. The square root of this figure will give you the diagonal measurement of our base rectangle. In this case the square root is 73.79 converted to 73’91/2””. Using the construction calculator is much easier. Enter 66, feet, run, 33, feet, rise, diagonal, which reads 73’91/2”” diagonal. Pull a tape from both hubs along a long side, cross the two tapes where 33’ meets

73’91/2”. Place a hub, mark and pin where the intersection is. For the fourth corner of the layout pull a tape from the known diagonal hub corners to the missing corner and where they intersect at 66’ and 33’ that is where the last hub and pin will be located. Before proceeding, check the two lengths, the two widths and the diagonals for errors. Run a string line around the perimeter of the layout rectangle. Now measure from the hubs along the string line and establish home layout points that are 3’ in from each hub along the perimeter layout string line, spike and paint or flag. This is where the batter boards will be located so strings can intersect at the actual corners of the home. Place strings from the inset pins to opposite pins where and continue for all 4 sides. From these string lines the chassis and marriage line points can be established and pinned. Once the layout is in this stage, the offsets and jogs can be located, but ground marking need not be highly precise since this layout is for footing excavation and the precision will be provided during the forming. Pulling a tape from the home corner string intersections, measure off all jogs and place flagged or painted spikes along perimeter string line to allow parallel strings for jogged walls. Measure out and spike jogs and other perimeter corners and bays. Remove the string from base rectangle and run a string taught and straight around the actual spiked home footprint, following the jogs as the home will. With marking lime or marking paint, mark the entire perimeter in preparation for the excavation. Each marriage line on the home will require an extra 5/16” approximately. I like to calculate this into the layout with the hubs, pins and batter boards but it can be added at the batter boards later. If you forget, the plate will need to be shimmed in width to match the home. With an offset, add the width to the shorter of the two sections. With a 3 section home, 5/8” works well and 1 1/8” for a 4 section home.

Intersecting tapes locate the third hub.

String the perimeter.

THE RIDGE BEAM SUPPORT FOOTINGS LAYOUT Manufactured homes require marriage line supports to carry the roof load from the center to half way out each roof section. Generally the home has a ridge beam support plan specific to each home sent with the home and available from the manufacturer. Be sure the home snow load is correct for the site and that you use support values for the correct snow load. Be sure the home dimensions are correct. It is common for homes to be custom stretched or even shortened. Make sure of the direction of the layout. First, measuring from the actual home corner spikes, locate the marriage line points, adjusted for section length as needed. Flag or paint, then starting at the end wall or offset end wall as determined by the plan, measure along the marriage line and locate the piers, size for correct value and mark with paint. The required footing size can be found in the foundation plan, the installation manual, the specific ridge support sheet.

If a pier size schedule is not available, the following formula will get you a correct size:

• Pounds of support required divided by 1000 psf soil support (or more if you can prove greater soil bearing capacity) #4 for example is 5990 lbs. divided by 1000 psf = 5.99 square feet required.

• The square roof of 5.99=2.447448 (the number when multiplied by itself equals 5.99). I use the square root key on a scientific or construction calculator for this.

• 2.45 rounded up multiplied by 12” (in a foot) equals 29.4” • The # 4 footing must be at least 29.4” x 29.4” or greater if the manufacturer

requires.

THE CHASSIS SUPPORT FOOTING LAYOUT Each manufactured home unit has 2 chassis rails or I beams per section. Chassis supports carry floor load from the center of each floor unit to the perimeter closest that rail. Chassis offsets are found by measuring the home or obtaining and verifying the dimensions from the manufacturer. Measurements range from about 16” to about 40” depending on the chassis rail width, distance from the rails to the sidewalls and any offsets that may be built in for shipping purposes. You must determine the distance from the side wall or marriage line for each rail. Mark the perimeter string line on the end wall accordingly. Chassis piers usually start from 1’ to 30” form the end wall and are typically spaced between 6’ and 12’ apart, depending on the manufacturer’s installation manual chart correctly picked for that unit. Determine the maximum distance from the end walls the footings may start. If there is a conflict, choose the shorter distance as it is a maximum, not a required distance. Footing spacing for chassis rails must be determined based on manufacture’s installation manual or foundation plan taking into account footing size, chassis rail size, soil bearing capacity and any other factors pertaining to the project. For instance a home 70 feet in length with a 12” chassis rail may require spacing at 8’ on center maximum with a 2’ maximum from each end. Take the 70’ length, subtract 2’ each end to get 66’. Divide 66’ by maximum spacing of 8’o.c. and you have the number 8.25. You must round up to 9 and add an end pier. It will need 10 piers per rail. Place a spike at the string line and run a tape measure from end to end along each chassis rail, securing it on the other end with no slack. Mark each point for the chassis rail. For instance, 2’,10’,18, 26’ etc. until the line is finished. Repeat the process on each of the chassis rails paying careful attention to which spikes are for the chassis and which are for marriage lines. .

Pulling tapes from the two long side corners intersect the tapes, place and mark a hub, confirm the dimensions and pin the hub.

The strings are now run from the offset pins and intersect at the home primary rectangle points. Note that the batter board stakes straddle these string lines/ also not that additional batter boards will be set up along the layout perimeter for the offset section walls.

Measuring the diagonals is done with the tapes held in this manner for accuracy. 1/8” tolerance is acceptable and will cause no trouble later.

While excavating, the bucket spills soil onto your chalk lines, so I mark well beyond the corner points so I can easily locate where to excavate.