We found that it holds 5lbs so far and potentialy more, considering our first bridge broke with a large ball of string as the weight and our second broke with a coke can. I think our success rate was pretty high

Bridge constructed with drinking straws & spaghetti.  Pinned connections between straws with spaghetti. Bridge span across deck = 50cm, supported below at half span. Was skeptical about the bridge holding the weight of the brick but it do so easily.