Building Confidence

Volume 17 Issue 12
ISSN 1923-7162

Welcome to Dave's Shop Talk's Home Improvement Newsletter of questions from our members on their construction projects, a Tip of the Month and a home remodeling article, both from our website at

Tip of the Month

Recycle used paint thinner. Place it in empty paint thinner containers and let stand for a month or two. Pour off the clean paint thinner carefully - this is a bonus!

And a Bonus Tip:

Without the use of a calculator: to convert inches to decimal feet, each inch is approximately .08 of a foot; such as: 1" = .08'; 2" = .17'; 3" - .25'; 4" = .33'; 5" = .42'; 6' = .50'; 7" = .58'; 8" = .67'; 9" = .75'; 10" = .83'; 11" = .92'; 12" = 1.00'. To convert 1/8" to a decimal foot, add .01 approximately for each 1/8" increment. Such as 1 1/8" = .08 + .01 = .09"; 1" = .08 + .02 = .10'; 1 3/8" = .08 + .03 = .11; 1" = .08 + .04 = .12'; 1 5/8" = .08 + .06 = .14; 1 7/8" = .08 + .08 = .16'; 2" = .17'. With a calculator: for 1 1/8" divide 1 by 8 = .125, add 1.0 = 1.125 which is divided by 12 = .09375 or to 2 decimal places = .09 of a foot.

Ask Dave!

Hi Dave I'm in Australia where we use metric - is it possible to get the plans in metric (ie 3000mm x 3000mm)? thanks Viviana

Hi Viviana,

Yes, I can convert the sizes for you, but first will you answer my questions on sizes:

Our 2x4 is your 4x2. What do you call it and what is its size? I've been researching the Bunnings Building Supply Website, a great resource! According to Bunnings the size is 100x50 with actual size 90x35. Is this correct? Would you go into a store and request a 90x35 or would you ask for a 100x50?

Is your plywood size 2400x1200x ?mm?

Is your average grade

Anything else that you could educate me on?

Thanks, Dave

Thanks Dave, I had to ask my husband for the answers: 1. 90mmx35mm 2. 12mm 3. yes MGP10 is the average grade Also we would use H3 CCA timber (it is for outdoor use and termite proof) and the posts would be H4 200mm round (outside, underground and termite proof). As for 'anything else' a standard indoor wall frame in Australia would be 70mmx35mm with a 70mmx45mm top and bottom plate. We spend lots of time and money at Bunnings! cheers Vivana

Hi Vivana,

Please find your Gazebo plan attached. I didn't go with the 12' conversion, because I realized that your plywood is a bit shorter than our 8'. With the measurement of 3600mm square, the plan fits your plywood size better. Don't hesitate to ask questions if you don't understand anything. We are not that far away on the cyber highway!

Happy Building,


Thanks Dave You are amazing! This is our Christmas project :)

Nice! Merry Christmas!



We added the new plans to our site that I sent to Viviana. We present them to you in this newsletter as our Feature "Article" of the Month:

Feature Article of the Month

(taken from our website:

Gazebo 3600mm Square with Hip Roof

These wood working plans include:

The following drawings with all measurements in mm:

  • Front Elevation showing framing of the rafters, the beam and posts, floor and footings.
  • Roof and Ceiling Plan showing the layout of the hip and jack rafters as well as the ceiling joist and beams.
  • Floor Plan showing the framing of the floor, footings and beams.
  • Side Elevation showing the rafters, beams and floor framing and footings.

The plans have a List of Materials, showing a breakdown of materials for the floor and roof.

The Instructions include the following topics:

  • The Foundation and Floor: The concrete footings and columns, beams, squaring the floor joists, applying tongue and groove plywood.

  • The Roof: Laying out the rafter positions on the beams.

  • The Common Rafters: The length of the common rafters including how to cut the bird's mouth.

  • The Hip Rafters: The length of the hip rafters and angle of the plumb cut.

  • The Hip Jack Rafters: The length and angles of the jack rafters.

  • The Ceiling: Installing the ceiling joists, fascia and roof sheathing.

Drawing of our 3600mm gazebo

Diagram of the roof and ceiling of our 3600mm gazebo showing joists, rafters and beams with measurements

Diagram of our 3600mm gazebo floor plan showing concrete footing and post, beam, box or rim joist, floor joists and blocking.

Diagram of our 3600mm gazebo side elevation showing common rafter, jack rafter, hip rafter, fascia board, ceiling joists, beam, brace, posts, floor joists, scab, and concrete footing and post with measurements

List of Materials

The Gazebo Floor:

  • 4 - 190x45x3600 beams
  • 6 - 90x35 posts doubled
  • 13 190x45x3600 joists and solid bridging
  • 5 sheets 2400x1200x17 tongue and groove standard sheathing plywood
  • 3 lbs 50mm common galvanized nails
  • 3 lbs 75mm common galvanized nails

The Gazebo Roof:

  • 12 - 240x45x3600 beams
  • 4 - 200mmx3000 Round posts
  • 4 - 90x35x3000 Braces
  • 4 - 190x45x3300 hip rafters
  • 4 - 140x35x2400 common rafters
  • 8 -- 140x35x3300 hip jack rafters
  • 4 - 140x35x4500 rafter fascia
  • 4 - 190x30x 4800 fascia board
  • 6 - 140x35x3600 ceiling joists
  • 1 -- 90x19x2400 Bridging on top of joists
  • 8 sheets 2400x1200x12 OSB or plywood sheathing
  • 3 lbs 50mm common bright nails
  • 3 lbs 75mm common galvanized nails
  • Roofing as desired - 20 square metres


The Gazebo Foundation and Floor

Let's start with the gazebo foundation. Orient the floor plan and elevations so you choose which side will be the front side of the gazebo. The front and back will look a bit better than the sides, since the overlap of materials doesn't show on the front and the beam is shown along its face rather than its ends, as on the side. I went with footings and 250mm square concrete posts. Also acceptable for the gazebo is a footing with 250mm round concrete piers made from sonotubes. The beam needs support in the middle of it so go with a 300x300 concrete pad or footing with a double 90x35 post supporting it. Nail the beams together with 75mm common galvanized nails at 400mm apart, top and bottom. The gazebo's concrete piers or posts should extend at least 150mm above any grade and extend below the frost line at the bottom of the footing. The 200mm posts should be attached to the top of the piers with the use of a post saddle or flat bars beside the posts, rather than embedding the post itself into concrete. Allow for the concrete posts' correct width so that the wooden 200mm post will be 3600mm exactly to the outside.

The gazebo floor is supported off concrete pads and 90x35 wooden posts under double 190x45mm beams. The gazebo roof is supported independently off triple 240x45mm beams on 200mm posts on a post saddle embedded in 250mm concrete columns on 400x400x140mm deep pads. Notice on the Front and Side Elevations that the 400x400x140mm posts under the floor beams share the 400x400mm footings in the corners with the concrete posts.

The gazebo's four concrete posts should be poured with their footings in place. Their elevation is not critical at this point, you can level the top beam by cutting the posts off level with the shortest one. Check each corner both ways before cutting.

Once the posts are installed and to the right height, the double 240x45mm beam can be installed. With any beam or joist make sure that the crown of the board is assembled on top, so when a load comes on top of it, it will settle down straight. Make sure the bearing of the beam has 75mm on the post. Assemble the beam perimeter first, then double up the beam on the inside. Make sure the outside of the posts and beams are 3600mm.

Diagram of post beam scab from side and front with nailing patternDepending where you live and the amount of wind or earthquake threat in your area, we should tie the beam of the gazebo to the posts more securely than just with toenails.

Referring to the drawing, the scab should be the same size as the post, a 140x35mm and nailed or screwed similar to the pattern shown. A 45 degree cut on the end dresses it up a bit. Leave a slight reveal of the square edge, as shown.

Now that the posts and beams are up and securely nailed, brace up the corners of the gazebo with temporary braces to hold everything plumb. The braces can be tied into 90x35mm stakes driven into the ground. These braces will remain in place until the gazebo roof is on and sheeted and nailed.

You can build the gazebo floor now or after the roof. It may be easier to work on the gazebo's roof, if there is a nice level floor to work off. Nail up the beams on both sides to support the floor joists. Level them as you install the posts. If the beams for the roof are level, you could measure down the post from on top of the beam to about 2823mm, if you want a 2450mm ceiling on your gazebo.

Cut 2 - 190x45s 3658mm and lay them both out together for the box joists. Start at the left end, measure 382mm (400 - half the thickness of the joist) and place a mark with an X on the right of the mark. Now move the tape to this mark and continue to mark and place an X in the same manner at every 400mm mark on your tape, until you run off the board. When you nail the joists onto this box joist the left edge of the joist will be on the mark covering up the X.

After nailing on all the joists you should be able to place your tape on the edge of any joist, except the first one, and read a multiple of 400mm. This will enable the plywood to end on the center of the joist. When the joists are all nailed on, measure their diagonals to be sure the gazebo floor is square. Bump one box joist to the left or right until the diagonals are the same and the floor of the gazebo is square. Go ahead and nail the plywood on. When using 17mm tongue and groove (T & G), we usually start with the tongue flush with the outside of the floor and the groove towards the inside of the floor. Since the gazebo floor will not have a wall over the edge, I would suggest you cut the groove off and add a filler to the other side. Unfortunately, tongue and groove plywood sheets are 1200mm wide including the tongue, so on a 3600mm wide floor the sheets are going to come about 50mm short of the width. I would suggest ripping the first 1200mm from the spare piece you have left and then ripping two other pieces with a groove in one edge. You can eliminate the grooving of a thin piece by buying another 2400x600 sheet from your local building supply. Usually a couple of passes through the table saw and a groove is cut out.

Notice the stamp on the plywood, it usually says place this side down (the tongue is thicker on the bottom). Nail on your first sheet, full length and a half sheet end to end, snug to each other. Just use a few nails to keep the plywood in place and mark where the joists are. Keep them back from the groove side by at least 150mm to allow the next sheet to slip into the groove easier. Install the third sheet, the other half of the second sheet and start on the left, the way you laid out the joists. Place the tongue up to the existing groove get your helper to stand on the tongue and groove together while you hammer lightly with a sledge hammer against a 90x35 against the groove side of the third sheet. The sheet should slip into the groove of the one nailed on. Now install the fourth sheet (full size) next to the half sheet. This is called staggering your sheets so the joints are not in the same line. Continue the next row with a full sheet, staggering your sheets again. Nail or screw on the plywood securely: nails spaced 150mm apart on all joints and 300mm apart in the middle.

The Gazebo Roof

Okay, time to cut some rafters. These measurements are dependent on the outside of the beams of the gazebo being exactly 3600mm.

Let's first layout the position of the common rafters and the jacks. Notice on the Roof Plan I put the ceiling joists in red. The purpose of the ceiling joists is to prevent the gazebo's posts and beams from moving out with a load on them. Whether you want a ceiling on your gazebo doesn't really matter, you can leave it open or install a ceiling of cedar boards or whatever.

Each corner of the gazebo will be marked the same, so come in 600mm and scribe a mark, then an X where the rafter will sit. We say in the trade, "600mm and away". This means that the 600mm mark comes before the X, the X is away from the corner and the mark. Okay, mark 1200mm and away with your X. Now mark 1800mm and come back 22.5mm off of center and the X is away. Mark all 5 rafters, on each wall, coming in from the corners. Don't worry about the ceiling joists for now. There will be no need for a ridge board since the gazebo's roof is square and only two sets of common rafters.

I'll give you the correct lengths as follows.

The Common Rafters of the Gazebo

Cut four full length with 22 1/2 degrees on each end, if you have a cutoff saw. The length is 1949.6mm to the outside of the beam and another 400mm to the end of the overhang less the thickness of the fascia, nailed to the rafter ends. I figured this thickness to be 35mm. Check the thickness of the timbers that you are using.

Diagram of common rafter for our 12 foot gazebo with measurements.Cut the bird's mouth as shown by sliding the square along the plumb cut line until 76mm is reached. Cut one rafter as shown and mark the others from this template. Cut two common rafters half (17.5) the thickness shorter. The two longer ones go together at the center and the two shorter ones go up against these two. It is good to have a helper when installing the rafters on the gazebo. One person is at the ridge the other at the beam line. The person at the ridge pulls the two opposing rafters together, making sure they form a tight plumb line together, while keeping the bird's mouth tight to the side of the beam. The one at the beam line toenails them into the beam, one toenail on each side using 75mm nails. The rafters are then nailed together at the ridge with 75mm toenails or screws. Notice in the Roof Plan the number sequence for installing the first four rafters on the gazebo.

The hips should be nailed in place next with 75mm toenails into the common rafters - two nails per hip.

Before carrying on, make sure the perimeter of the gazebo is square. Check this by measuring the diagonals. They should be the same. The hips won't all be the same length if the roof isn't square.

The Hip Rafters of the Gazebo

Diagram of hip rafter for our 3600mm gazebo showing plumb cuts, bird mouth with measurements and angles.

The hips should be nailed in place next with 75mm toenails into the common rafters - two nails per hip, on each end.

When making the hips of the gazebo, notice that the new plumb cut for a hip is 16 1/2 degrees not 22 1/2 like the commons. The hips also will be cut on about a 44 degree on the sides. When nailing the hip to the intersection of the common rafters drop the hip a bit so the edges are the same level as the common. The bird's mouth is dropped down to allow for the edges of the hip being higher than the center by about 6mm, also trim off 50mm of the tail of the hip to 140mm, before measuring the 36.5mm for the depth of the seat cut. All measurements are on center line on the top edge of the hip as shown.

The Gazebo's Hip Jack Rafters

Diagram of hip jack rafter for our 3600mm gazebo with measurements and angles.

The best way to cut the jacks of the gazebo is to cut the side cut near the center of the board. This way you can use the same cut on the other end of the board, turn it over and use it for the opposite jack. To cut the side cut angle that goes against the hip, if you have a compound bevel and miter saw, cut the miter 46 degrees and the bevel at 22 1/2 degrees. Notice I gave you the length of the long angle. To cut the tail of the jack, use your common rafter template and scribe the bird's mouth and tail cut exactly as for the common rafter. Vary the measurements from the ones above as shown for the two sets of jacks. There are only two sets of opposite jacks since all four corners of the gazebo are the same. When nailing in the jacks install them in pairs making sure that the hip remains straight. Just site along the hip and hammer the jack tighter to move it over a bit if necessary.

The Gazebo Ceiling

Now that all the rafters are in place on the gazebo, install the 140x35 ceiling joists to tie them all together. Watch the Roof Plan for the direction they go as referred to by the side or the front. Notice the 3600mm joists, tie the beams together, but across the other way we need to tie these beams together, as well. For the joist going across the gazebo nail in solid blocking and fasten a 2500mm length of 90x19mm across the top to tie the blocking to the joists on each side. This way the beams are tied in both directions.

Make sure you nail the joists to the side of the rafters and into the double beam, as well. Try to stay on the side of the rafter that is shown, this way the joists of the gazebo will be uniform if a ceiling is later desired.

If a closed ceiling is desired on your gazebo add a 90x35 joist at the corners to cut the span down from 1200 to 600mm. Backing is nailed on the top of the beams to provide nailing for the ceiling where it parallels the beam. This backing is usually a 140x35 nailed on the flat with half of it overhanging the beam and the other half nailed onto the beam. Notice you need to cut off the top of the ceiling joists where it projects above the slope of the roof. A reciprocating saw is good for this.

Nail the 140x35 fascia into position flush with the underside of the rafters. Sheet the roof with 12mm OSB or plywood. Apply your choice of shingles as suggested by the manufacturer on the bundles. No need to add a heavy eave protection if the gazebo is not heated.

Remove the temporary braces and enjoy your new gazebo.

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(Ask Dave) (About Dave)

Your source for building tips, woodworking & furniture plans, house plans and building advice directly from Dave...

Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.


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