A Garuda tent! They came out, what, 10 or 12 years ago? I got to know the founder of the company, Byron Shutz, fairly well. He got an offer to sell his company to Dana Designs, of the famous Terraplane pack, back when it was owned by Dana Gleason. He was going to go along as part of the deal, but at the last minute backed out. Dana tried to make the tents go, but without Byrons influence they sort of petered out. So too did Dana Designs; its now part of Marmot, which is in turn part of K2 Sports.
I hope Byron still is in the industry somewhere. His tents were among the most beautiful ever made, with subtle, autumnal color schemes of golden-yellow and maroon; sleek lines that always reminded me of some sort of sea creature just emerging from the deep; and evocative names such as Jalan Jalan or Kamet. Alas, they were rather insanely expensive, using one of the high-cost waterproof-breathable fabrics that back then seemed to be the only solution to creating useful single-wall tents. And by modern standards, they werent even all that light. I bought one of Bryons one-person modelsthe Jalan Jalanjust before he sold the company, for sentimental reasons. I still have it, and it weighs a good four pounds.
So, as to your problem: The fabric used in the Garuda tents is a laminatea fabric sandwich, if you will. I believe it was two-ply, with the waterproof layer bonded to an inner layer that was lightly brushed to hold moisture and allow it to dissipate slowly through the tent wall. What is happening is that the fabric is de-laminating. You dont mention how much of it is de-laminating. If its a small patcha square foot or lessyou might be able to use something like McNetts Silnet Seam Sealer ($7; info at mcnett.com, buy at rei.com) to glue the fabric back together. If its a larger area, I think youre screwed. I happen to think youre screwed anyway. Chances are the whole thing is going to start coming apart soon. Tents simply dont last forever.
To be honest, single walls have come a long ways then, especially in the fabric department. Some now use totally waterproof/non-breathable materials that employ superior ventilation designs to get moist air out. Mountain Hardwears one-person Skypoint 1 ($220; mountainhardwear.com) is such a tent, and it weighs a mere two pounds, four ounces. You also can buy tents that are not strictly waterproof, but so water-repellent that youd have to be in days-long rain to get wet. Black Diamonds Lighthouse ($379; bdel.com) is made with Epic fabric, a material in which the threads are all individually coated. It breathes just enough to keep the interior dry, but costs much less than GoreTex-like materials. The Lighthouse sleeps two and weighs just over three pounds. Not bad! Ive been using one this summer and like it very much.