I'm wanting to volunteer abroad, in which I hope to help make a difference ie building houses for people. I want to go for a month however I haven't found any relevant volunteering projects that can help me with this as yet. Can anyone recommend some projects?
Frontier is more focussed on conservation and environmental projects, but it does occasionally have construction/building initiatives.
These are the only two that I know of, but neither are cheap. Hopefully someone else can chime in with some other options for you.
I did a volunteer program in nepal with world youth international (not religious). We built a water tank for the village we were staying at (home stays).
Had a great time!
It's really tempting to start with the big companies like those mentioned earlier when you start out with volunteer travel, but I'd avoid them if you can. I've done a couple of projects with them and I've never been sure where the large amount of money I paid actually ended up going. It's more worthwhile to spend more time doing some real research and finding small, local organisations that are genuinely rooted in the local community. I spent an incredible three weeks with Chandra Niwas in Udaipur doing cultural classes as well as volunteering in their youth centre and doing touristy stuff at the weekends. It was a far more personal and realistic experience than any of the ones I had with big companies, as well as being cheaper. I'd look into something like that.
This site has a ton of links throughout South America where you can volunteer very cheap. Just place your cursor over each link to read about their cause.
Personally I can voucher for SKY Ecuador on that list, where I spent about 4 months, teaching in a Kichwa/Spanish school and we were building a greenhouse in the village to raise funds for the school. It's not really what you're looking for, but I'm sure there's plenty of links that that will suit your fancy.
I second Philippa in suggesting that you stay away from the really large organizations. I truly believe they are doing their best for their respective causes, but by the very nature of being larger, they end up having business overhead costs that you might be unwillingly paying towards, and besides, they are able to recruit many more people. A lot of the grassroots projects have very little overhead and much trouble attracting volunteers.
Hope this helps