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How to Fix a Sagging Barn Roof: Illustrated Guide

Joy worked in construction for 7 years alongside her husband (25+ yrs. experience)—working on pole barns, grain bins, and barn repairs.

How Much Repair Is Needed?

The barn in question is not in horrible condition, but was becoming swaybacked, and would eventually have fallen in on itself if proper repairs had not been done.

I was pleased when my husband and I were called to fix the sagging roof. The barn was still being used for animals and equipment storage, and had all the marks of a long, evolving life.

Some roofs will be worse than this one, and will necessitate more tools, time, and materials to put right. This fix took about half a day. If your roof is seriously sagging, you may need a come-along in order to winch the sides of your building back into place, before you add bracing. Some barns require at least one come-along as a permanent fixture, strung across the haymow, to keep them from continuing to buckle outward.

Before: The barn in question is old, but still in use. We repaired the roof in the spring of 2009. This photo was taken prior to the repair.

Before: The barn in question is old, but still in use. We repaired the roof in the spring of 2009. This photo was taken prior to the repair.

After: This photo was taken just after the barn was reshaped through use of wooden braces.

After: This photo was taken just after the barn was reshaped through use of wooden braces.

Incomplete Photos, But Enough to Help!

Hopefully, the following pictures and instructions will help you figure out how to fix your own sagging roof.

The Extent of the Damages to the Barn Roof

There were three sheets hanging down inside the barn toward the front end. Each of these old sheets was 2' wide.

There were three sheets hanging down inside the barn toward the front end. Each of these old sheets was 2' wide.

The remainder of the cement block structure was in fair shape.

The remainder of the cement block structure was in fair shape.

The peak of the roof had pulled apart as much as 3" in places, and the roof sagged as much as 8".

The peak of the roof had pulled apart as much as 3" in places, and the roof sagged as much as 8".

Tools and Supplies

  • Carpenter's pencil
  • Circular saw
  • Chalk box, optional
  • Nail gun
  • 16-penny cement-coated nails for use with all lumber (nail gun strips)
  • 2-inch roofing nails for plywood . . .
  • . . . or 8-penny nail gun nails, 12-penny if you prefer
  • Screw gun, if needed
  • 2'x6' lumber—the amount will vary according to your situation
  • OSB board or plywood at least 1/2" thick—the number of sheets will vary. 5/8" or 9/16" thick is best.
  • Replacement roof materials and corresponding hardware, if needed
  • Imagination, a sense of humor, a good temper, patience, and, lastly, common sense

If Installing Metal Roof Sheets

  • 2" sheet metal screws
  • Screw gun
  • Appropriate metal roof sheets
  • Tin snips
  • Electric metal shears, optional—if needing to trim sheets lengthwise, they make the job clean and fast, especially on high ribs
  • Square or straight edge, for marking screw lines across sheets in line with purlins

Overview of the Construction Process

Your goal is to strengthen and reshape the roof through means of wooden braces, 2'x6' lumber, possibly new or added purlins, and maybe a come-along manual winch.

You will use a hydraulic floor jack to lift a long 2'x6' against strategic points along the roof to nudge the roof back into shape. Then you will make triangle-shaped braces from plywood or OSB, and install them under the ridge. If needed, a come-along can gently be used to help pull the barn into shape by hooking it to the walls.

After these changes, your barn should maintain its shape well enough not to be a danger to occupants, and you should be able to follow up with other roof or structural repairs.

Stage 1: Placing the Bottom Part of the First Brace

  1. Using a 2'x6' and a floor jack, we gently pushed a small section of the roof level.
  2. We used preexisting structural materials to take measurements for the new structural reinforcements.
  3. Take accurate measurements at crucial points on the structure—this means at the apex of the roof and at both corners. Write them down. These measurements are necessary for cutting the OSB.
Using a 2'x6' and a floor jack, gently push a small section of the roof in to a level position. We started where the roof showed the least amount of damage.

Using a 2'x6' and a floor jack, gently push a small section of the roof in to a level position. We started where the roof showed the least amount of damage.

Cut ends square and nail the 2'x6' solidly to the existing supports.

Cut ends square and nail the 2'x6' solidly to the existing supports.

Take accurate measurements at crucial points along the structure. These include the length of the brace, from the top edge of the 2'x6' to the peak, and at least one point along the slope, so you can mark accurate lines on your plywood or OSB board.

Take accurate measurements at crucial points along the structure. These include the length of the brace, from the top edge of the 2'x6' to the peak, and at least one point along the slope, so you can mark accurate lines on your plywood or OSB board.

Measurement checkpoints must be measured accurately. Write them down; don't trust multiple measurements to your memory.

Measurement checkpoints must be measured accurately. Write them down; don't trust multiple measurements to your memory.

Making Wooden Braces: Cutting and Placing the Plywood Triangle on the First Brace

There is no magic to making triangle braces. Careful measurements and a reasonably snug fit are required, but beyond this, what you need to do is whatever works.

The 2'x6' lumber itself does not substantially hold the barn; the triangle of plywood or OSB does that. The lumber is there to stabilize the triangle, which will, in turn, uphold and shape the barn roof.

Mark the plywood accordingly. We are using 5/8" OSB. Thicker would be better.

Mark the plywood accordingly. We are using 5/8" OSB. Thicker would be better.

Using a chalk box to mark lines makes the process efficient, but using a large square or straight edge and a carpenter's pencil works too.

Using a chalk box to mark lines makes the process efficient, but using a large square or straight edge and a carpenter's pencil works too.

A circular saw with the blade set just deeper than the depth of the board works well for cutting the OSB.

A circular saw with the blade set just deeper than the depth of the board works well for cutting the OSB.

A good blade is crucial for a neat cut.

A good blade is crucial for a neat cut.

Use a nail gun to fasten brace to the rafters, but not to the 2'x6' brace. The 2'x6' is there only to hold things together until the triangle brace is in. The triangle sits on it. Shoot nails in at an angle, deep into the rafter and through layers.

Use a nail gun to fasten brace to the rafters, but not to the 2'x6' brace. The 2'x6' is there only to hold things together until the triangle brace is in. The triangle sits on it. Shoot nails in at an angle, deep into the rafter and through layers.

Do a good job, and don't be shy using those nails.

Do a good job, and don't be shy using those nails.

Stage 2: Repeat Bracing as Needed

The first section is complete. The next few steps, depending on the roof, will be very similar.

You will keep reshaping the roof a bit at a time with the long board and hydraulic jack, pausing to make more custom braces as you go.

The first step of stage two is to place the long board to support the roof sag again! This will allow you to remeasure for each new brace and eliminate the ridge gap.

Position the floor jack under the next joist or rafter.

Position the floor jack under the next joist or rafter.

Set the 2'x6' squarely on the jack, wedged slightly against the roof.

Set the 2'x6' squarely on the jack, wedged slightly against the roof.

Lift roof gently, as before.

Lift roof gently, as before.

Holes Along the Ridge

How much gap needs to be sucked out along the ridge in order for your ridge cap to work properly? In new construction, a gap up to 4" wide is sometimes left. However, in this example repair, we tried to remove all the gap we could, resulting in 2" to 3" toward the peak of the barn.

If you get the gaps down to 2", your building should become weather tight with proper installation of a new ridge cap, and foam closure strips. Ridge cap trim is usually a total of 11" wide.

We used a second board to help temporarily brace this section of roof. As you can see, it has a long ways to go to become level and stop gapping.

We used a second board to help temporarily brace this section of roof. As you can see, it has a long ways to go to become level and stop gapping.

Here the roof has been pushed up nicely, and we are ready to measure for a brace.

Here the roof has been pushed up nicely, and we are ready to measure for a brace.

The first brace is secured, but will still allow some settling and adjusting between it and the next brace.

The first brace is secured, but will still allow some settling and adjusting between it and the next brace.

Some of the wood is warped from torsion and exposure, but will still come right enough to make a good roof again.

Some of the wood is warped from torsion and exposure, but will still come right enough to make a good roof again.

Distinct Brace Measurements

Each brace's measurements are likely to be slightly different than the one before, and you should never assume that what you did for the first brace will serve the others. Treat each as an individual, just as you did the first.

Measure and install a 2'x6', as before.

Measure and install a 2'x6', as before.

These braces are fairly even lengths, but it's okay if yours are not all the same. Remember that your primary objective is to strengthen the roof, and that bigger braces where possible are better than uniform braces.

These braces are fairly even lengths, but it's okay if yours are not all the same. Remember that your primary objective is to strengthen the roof, and that bigger braces where possible are better than uniform braces.

Mark a new baseline on your plywood so that you can flip the placement of your triangle opposite of the first one. Measure how wide this brace will need to be from peak to base, to make sure your baseline is placed far enough out.

Mark a new baseline on your plywood so that you can flip the placement of your triangle opposite of the first one. Measure how wide this brace will need to be from peak to base, to make sure your baseline is placed far enough out.

Installation of the triangle is similar to the first brace.

Installation of the triangle is similar to the first brace.

You can see in the gap the old nails which pulled out of the ridge.

You can see in the gap the old nails which pulled out of the ridge.

Finishing the Second Brace

The roof is looking much better than it did at the beginning of the project but is only about halfway done. More bracing is required, also purlins need to be added, roof sheets must be replaced, and ridge cap extended.

Section three is similar to the first two, except that every effort should be made to get as much remaining gap out as possible.

Section three is similar to the first two, except that every effort should be made to get as much remaining gap out as possible.

The main braces are finished, but further strategic bracing is needed. Also, some work is needed to replace roof sheets and the ridge cap, which has been torn.

The main braces are finished, but further strategic bracing is needed. Also, some work is needed to replace roof sheets and the ridge cap, which has been torn.

Stage 3: Jacking Up and Bracing the Third Section for Additional Bracing

More bracing can be put where needed. In our case, we installed new purlins between rafters toward the front of the barn, where the entire structure had disintegrated, and metal roof sheets had disappeared.

This fix was fairly straightforward, but if yours is trickier, use whatever ingenuity you need to in order to make your building safe and reliable.

In order to have something to attach roof sheets to, it is necessary to install short 2'x6' purlins.

In order to have something to attach roof sheets to, it is necessary to install short 2'x6' purlins.

These are nailed securely to whatever solid lumber is left.

These are nailed securely to whatever solid lumber is left.

Put nails at an angle into both ends, and also on both sides of each board (not shown).

Put nails at an angle into both ends, and also on both sides of each board (not shown).

Spacers and shims of scrap lumber were made to align each purlin with any original rafters and purlins, as necessary.

Spacers and shims of scrap lumber were made to align each purlin with any original rafters and purlins, as necessary.

Careful measurements and checking fit of purlins is important. They must not gap excessively.

Careful measurements and checking fit of purlins is important. They must not gap excessively.

Some purlins had to be wedged into tricky areas, and you can see that they are not perfect. Do the best you can.

Some purlins had to be wedged into tricky areas, and you can see that they are not perfect. Do the best you can.

Roof sheets have been installed using 2" sheet metal screws. Ridge cap will come later, but for now the barn is serviceable for many uses.

Roof sheets have been installed using 2" sheet metal screws. Ridge cap will come later, but for now the barn is serviceable for many uses.

The Roof Is Back Where It Belongs

Though not fully restored, this barn is at least basically leveled and weather-resistant.

Though not fully restored, this barn is at least basically leveled and weather-resistant.

King County Barn Preservation Program

Using a Come-Along

If a come-along is required in order to pull the barn together enough for the roof to meet, the following is a good way to attach it.

Insert lag bolts near the ends of two lengths of 3/8" or 1/2" diameter chain, securing the chains to the insides of your barn loft walls opposite each other. The chains should have hooks. Secure your come-along between the chains, and draw the barn back together by degrees.

If your barn starts to creak, groan, pop, or yell excessively—STOP! You can wait several hours or a couple of days, wait for adjustments to take place, and pull the building together a little more. A building whose bones hurt may require several days to put right.

Whatever you do, please use common sense, and don't damage your barn further, or cause it to collapse on anyone.

A come-along can be used in conjunction with the jacking method shown here.

If you believe your barn may not be fixed permanently by merely installing braces, you may install at least one come-along permanently in the haymow.

More Damage Means More Bracing

The steps shown here can be repeated as far along your roof as necessary. Continue jacking, bracing, and aligning through all the affected roof sections.

We haven't had a call-back, and the customer seems satisfied whenever we see him around, so we can say that this has been a successful repair!

Do you have experience fixing a roof or do you need a roof fixed? Leave your questions and experiences in the comments below!

Restored Barn Transformed Into a Home

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2019 Joilene Rasmussen

Comments

Joilene Rasmussen (author) from United States on July 12, 2019:

Renovationhyderabad, thanks! I'm happy to be of use!

renovationhyderabad on July 12, 2019:

Informative

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