How to draw parallel lines on ceiling?

[ventodimare]

I need to draw multiple parallel lines on a big ceiling. Taking measures from the vertical wall is gonna take ages as the ceiling is big. I tried to use the bosh cross level but the line on the ceiling doesn't look parallel to me (see pic). Any idea please?

Thanks a mil

 

[Noyade]

Old school @ventodimare 

I was thinking two people.

Two step ladders.

One holds the end of a tape measure and moves along marking as they go.

Repeat for the other side of the room.

Cheers.

[JacobZ]

Hi @ventodimare,

Thank you for your question about marking out parallel lines on your ceiling.

It's great to see @Noyade has jumped in to offer some advice which I completely agree with. While it is possible to mark out a ceiling alone, having someone to help you will always make it easier. With two people, a chalk line becomes an option that makes transferring lines to the ceiling much easier.

To speed up the marking out process, a lot of the work is understanding the shape of the room by determining whether the walls are plumb (level vertically), and the room is square. If the walls are plumb, any marks you need to make on the ceiling can be made on the floor. If the walls are square to each other, then you can make two marks equal in distance from the wall on the left and then join the marks together.

Start by working out if the walls are plumb. Place a spirit level that is at least 1200mm long on the wall vertically in a few different places along the wall to determine if it is plumb.  If it is plumb, any mark made on the ground will be the same distance from the wall as it is on the ceiling. If the wall is plumb, then you place your laser level between the marks on the floor to "join the dots" and then transfer the marks to the ceiling. See the below photos for a visual representation of what I mean.
 

If the room is square, then this process can be followed the whole way across the room. If you measure the width of the room from the far-left corner and the front-left corner in my 3rd image and find they are the same measurement, then the room is square. If they are not the same, then you will need to determine what you want the lines to be parallel with.

Start by checking the room for plumb and square and let me know how you go. If you run into any further questions, please let me know, I'd be happy to advise further if required.

Jacob

[Nailbag · Accepted solution]

Hi @ventodimare 

Just in regards to using/trusting your cross-hair laser. It only takes a fraction of being off-square with it being in its position relative to the wall/ceiling to be offline, which is amplified the longer the distance. So you could start by using the marking technique that @JacobZ provided at each end of the room to produce master lines on the floor. Then position your laser roughly in the middle of each one and align the laser line with the markings. The lines will then be accurately reproduced up the walls and ceiling.

You can't see my floor and wall markings, but this was the basic technique I used to set up straight guidelines using my laser for a lined ceiling that was out of square.

Of course @Noyade old-school method will work just as well!

Nailbag