Top stitched french seam questions

1 – there are two rows of stitches plus the fold (from the second picture).  At the fold the two pieces are sewn together so you can see that seam also.  It’s sort of hidden.

It seems like a regular flat felled seam (or what some people call a faux flat felled seam) would be better – you don’t have that extra fold with a hidden seam.  And there are only two rows of stitches.

2 – if it’s a ridge I wouldn’t bother seam sealing because it’s on a ridge – no water flowing down across it.  Only when a raindrop just happened to fall on it.

I think most people would seam seal it though.  Are you using silnylon or silpoly?  Then use silicone seam sealer.  A little easier to seal a flat felled seam. On the outside.

3 – where are the grosgrain loops?  On the corners and sides of the tarp?

Hello Jason,

Ive only just made my first tarp, so this is NOT the voice of experience. (Have taken it on a 4 day rainy snowy walk and it did well.)

I used the same seam you are planning- I liked how (relatively) easy it was to manage.  I placed the bulk of the seam on the outside of my fly (found some online posts, including from a cottage manufacturer, which suggested it) – it probably doesnt matter enormously ?

I seam sealed from the outside… I didn’t want water to get into the folded outside section.

I sewed on my ridgeline grosgrain loops after sewing the ridgeline  seam. I made matching loops on the inside and outside so the stitching goes through grosgrain then tarp then grosgrain. I wanted loops both sides, but it also seemed good to have the reinforcement of the 2nd layer of grosgrain.

I think there are probably lots of different ways to do it that work fine.

Hope it goes well for you!

Cheers.

Thank you, Jerry and Megan!

1. I thought about the flat felled seam and made several practice runs with moderate success; the French seam was much easier to do well for me. I’m pretty new to sewing and will probably revisit the flat felled seam once I’ve had some more experience.

2. It’s good to hear that I might not need to seam seal. I will make and test it before I decide on whether to seam seal. I’m still interested in other’s experience with how they seam seal this type of seam.

3. The loops would be along the ridgeline, on the underside of the tarp. I don’t intend to have loops along the outside of the tarp ridgeline. Since they would just be used to connect a bivy or net tent, there shouldn’t be too much stress. I will probably just sew them onto the ridgeline since there will be five layers of material I imagine it should hold.

top stitch french and flat felled are very similar functionally, so if one is easier, then that’s good

that’s a good idea to have grosgrain loops inside, yeah, not too much stress

you could set up tarp with as much tension as possible to stretch it out, apply permatex or silicone diluted with mineral spirits assuming you have sil fabric.  From the outside.  Work it into the thread of the seams.  Let cure for a day.

You could not seam seal.  Use it on a few trips.  Any leakage would be minor.  Seal it if there’s too much leakage.

The only time I’ve had a leakage was where I sewed a grosgrain loop to the fabric half way down from the top.  Then, water went through and dripped onto me down below.

I use an inside ridgeline. I may be missing something, I’m not well practiced,  but I find using a tarp as the main support for a bivy tends to compromise both.